Polyethylene and Process For Production Thereof

ABSTRACT

This invention relates to a process for polymerizing olefins in which the amount of trimethylaluminum in a methylalumoxane solution is adjusted to be from 6 to 25 mole %, prior to use as an activator, where the mole % trimethylaluminum is determined by  1 H NMR of the solution prior to combination with any support. This invention also relates to a process for polymerizing olefins in which the amount of an unknown species present in a methylalumoxane solution is adjusted to be from 0.10 to 0.65 integration units prior to use as an activator, where the unknown species is the peak is identified in the  1 H NMR spectra of the solution performed prior to combination with any support. Preferably, the methylalumoxane solution is present in a catalyst system also comprising a metallocene transition metal compound.

FIELD OF THE INVENTION

This invention relates to polyethylene resins and catalyst and processesfor the production thereof.

BACKGROUND OF THE INVENTION

Ethylene-based polymer materials are generally known in the art. Forexample, polymers and blends of polymers have typically been made from alinear low density polyethylene (LLDPE) prepared using Ziegler-Nattaand/or metallocene catalyst in a gas phase process. Films made fromconventional Ziegler-Natta catalyzed LLDPE's (ZN-LLDPE) are known tohave favorable physical properties such as stiffness, lifting abilityand tear resistance, but poor impact resistance. Films made frommetallocene catalyzed LLDPE (m-LLDPE) are known to have superior impactresistance and suitable stiffness, but often suffer from drawbacks, suchas low tear strength, in both the machine and transverse filmdirections, compared to films prepared with ZN LLDPE. Thus, the filmindustry has sought metallocene catalyzed film resins that exhibitfavorable stiffness and tear resistance similar to, or better than,those prepared using ZN LLDPE resins, while retaining the superiorimpact resistance of films prepared using m-LLDPE reins. Specifically,the film industry wants films having a stiffness exceeding 200 MPa andboth MD Elmendorf Tear and Dart prop values equal to or exceeding 20g/micron.

The film industry is still in search of methods and compositions thatovercome these shortcomings and provide improved physical properties,improved processability, and an improved balance of properties.

U.S. Pat. No. 6,242,545 describes a process for the polymerization ofmonomers utilizing hafnium transition metal metallocene-type catalystcompound. The patent also describes the catalyst compound, whichcomprises at least one cyclopentadienyl ligand including at least onelinear or isoalkyl substitutent of at least three carbon atoms.

U.S. Pat. Nos. 6,248,845 and 6,528,597 describe single reactor processesfor the polymerization of monomers utilizing a bulky ligand hafniumtransition metal metallocene-type catalyst compounds. These patents alsodescribe an ethylene polymer composition produced by using bulky ligandhafnium metallocene-type catalysts.

U.S. Pat. No. 6,956,088 describes metallocene-catalyzed polyethyleneshaving relatively broad composition distribution and relatively broadmolecular weight distribution. Specifically, U.S. Pat. No. 6,956,088discloses thin (about 0.75 mil, 19 micron) blown films made fromethylene polymers made using a bis(n-propylcyclopentadienyl) hafniumdichloride and methylalumoxane that are reported to have a superiorbalance of stiffness, tear resistance, and impact resistance. However,this superior balance of properties can only be obtained under selectedfilm fabrication conditions requiring extensive draws and high stretchrates. The metallocene-catalyzed polyethylenes of U.S. Pat. No.6,956,088 lose their superior balance of film properties when made undertypical draws and stretch rates used to make the majority of commercialfilms. In addition, these polyethylene films lose the superior balanceof film properties as the gauge of the film is increased to be greaterthan about 0.75 mil (19 micron).

U.S. Pat. Nos. 6,936,675, and 7,172,816 describe polyethylene filmsproduced from a polymer obtained using a hafnium-based metallocenecatalyst. Methods for manufacturing the films are also described. Thesefilms do not have a balance of softness (lower 1% Secant Modulus),greater lifting ability (Tensile at Yield), and lower UltimateStrain/Ultimate Stress ratios.

U.S. Patent Application Publication No. 2008/0038533 (specificallyExamples 46, 47 and 48) discloses films made from polyethylene made fromcatalyst systems disclosed in U.S. Pat. No. 6,956,088. These films donot have a balance of softness (lower 1% Secant Modulus), greaterlifting ability (Tensile at Yield), and lower Ultimate Strain/UltimateStress ratios.

U.S. Pat. Nos. 7,179,876 and 7,157,531 disclose films made from ethylenepolymers made using a bis(n-propylcyclopentadienyl)hafnium metalloceneand methylalumoxane. These films do not have a balance of softness(lower 1% Secant Modulus), greater lifting ability (Tensile at Yield),and lower Ultimate Strain/Ultimate Stress ratios.

This invention provides polyethylene and films thereof having improvedphysical properties, improved processability, and improved balance ofproperties.

Likewise, trimethylaluminum (TMA) has been used in some polymerizationsas a scavenger, although some gas phase polymerizations prefer noscavenger such as TMA (see U.S. Pat. No. 6,956,088, column 5, lines18-25, citing WO 96/08520).

Methylalumoxane (MAO) is often used as an activator with metallocenecatalyst compounds and one common method of making MAO is the hydrolysisof TMA. Such hydrolysis however tends to leave residual TMA in the MAOwhich can have negative affects on polymerization.

WO 2004/108775 discloses “[α]dditional components, such as scavengers,especially . . . alkylaluminum dialkoxide compounds and hydroxylcontaining compounds, especially triphenylmethanol, and the reactionproducts of such hydroxyl containing compounds with alkylaluminumcompounds, may be included in the catalyst composition of the inventionif desired.”

Others have noted that an increase in amounts of AlMe₃ in MAO candecrease catalytic activity in a number of systems, such as ring-openingpolymerization of beta-lactones (see Organometallics, 1995, Vol. 14, pp.3581-3583, footnote 5) and that trimethylaluminum does not appear to actas a co-catalyst (see Macromol. Chem. Phys., 1996, Vol. 197, pp.1537-1544).

The reaction of triphenylmethanol and trimethylaluminum is disclosed inHarney D. W. et al., Aust. J. Chem., 1974, Vol. 27, pg. 1639.

This invention also provides a process utilizing TMA in combination withMAO to achieve enhanced polymerizations as well as enhanced productproperties, such as enhanced tensile performance of polyethylene films.The processes disclosed herein offer the previously unknown ability toalter polymer microstructure and physical properties by manipulating theamount of TMA, or unknown species (defined below) in a MAO/TMA solution.This process also offers on-line control in a continuous process forcontrol of polymer microstructure and physical properties.

SUMMARY OF THE INVENTION

This invention relates to a process for polymerizing olefins in whichthe amount of trimethylaluminum in a methylalumoxane solution isadjusted to be from 1 to 25 mole %, prior to use as an activator, wherethe mole % trimethylaluminum is determined by ¹H NMR of the solutionprior to combination with any support.

This invention also relates to a process for polymerizing olefins inwhich the amount of an unknown species present in a methylalumoxanesolution is adjusted to be from 0.10 to 0.65 integration units, prior touse as an activator, where the unknown species is identified in the ¹HNMR spectra of the MAO solution prior to combination with any support.

This invention also relates to a method to produce block copolymerscomprising adjusting, preferably adjusting on-line, the amount oftrimethyl aluminum in a methylalumoxane solution prior to use,preferably in a continuous process, as an activator to obtain comonomertriad [HHH] fractions in the different segments (also referred to asblocks) that differ by at least 5% relative to each other.

This invention also relates to a copolymer comprising ethylene and from0.5 to 25 mole % of C₃ to C₂₀ olefin comonomer, said copolymer having: atensile stress at the secondary yield point of 1.5 MPa or more; a ratioof ultimate tensile strain to ultimate tensile stress of 19.9 or more; atensile stress at 200% elongation (MPa) that is greater than the tensilestress at the at the secondary yield point (MPa); a comonomer triad([HHH] triad) of 0.0005 mole % or more (preferably 0.0006 mole % ormore); a density of 0.910 g/cm³ or more; and a 1% secant modulus of 30to 100 MPa.

This invention further relates polyethylene resins and to thepreparation of said polyethylene resins (typically copolymer comprisingethylene and from 0.5 to 25 mole % of C₃ to C₂₀ olefin comonomer),having improved tensile properties by polymerizing ethylene andcomonomer (such as hexene) together using a catalyst having as atransition metal component a bis(n-C₃₋₄ alkyl cyclopentadienyl) hafniumcompound and selected amounts of aluminum compounds wherein the polymerproduct has: 1) a ratio of Ultimate Tensile Stress to Tensile Stress at100% elongation of 2.4 or more; 2) a ratio of Ultimate Tensile Stress toTensile Stress at 300% elongation of 2.5 or more; 3) a ratio of UltimateTensile Stress to Tensile Stress at the primary yield point of 2.9 ormore; 4) a density of 0.910 g/cm³ or more; 5) a 1% secant modulus of 30to 100 MPa; and 6) a Tensile Stress of Y MPa or more, whereY=(0.0532)*Z−8.6733 and Z is the percent strain and is a number from 500to 2000, preferably from 500 to 1000, preferably 500, 550, 600, 650,700, 800, 850, 900, 950, or 1000, preferably 500. AlternatelyY=(0.0532)*Z−9.0, alternately Y=(0.0532)*Z−9.5. See FIG. 6, where, forexample, the stress at 800% strain is approximately 33.9 MPa.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is the ¹H NMR spectrum of the MAO (30 wt % in toluene) used inthe Examples.

FIG. 2 is the baseline adjusted ¹H NMR analysis of the MAO in FIG. 1 ascalculated by Bruker XWIN-NMR version 2.1 software using the polynomialfunction.

FIG. 3 is a graph of the ratio of the relative low density component'sloading to the higher density component's loading as a function of theamount of Hafnium in the catalyst at different Al/Hf mole ratios. Thehexagon is Example 44.

FIG. 4 is a graph showing the aluminum loading versus the hafniumloading. The circle is Example 44.

FIG. 5 is the [HHH] triad loading versus the amount of an unknownspecies in the catalyst. The [HHH] triad loading increases with anincrease for unknown species in the catalyst.

FIG. 6 is a graph of the Tensile curves for compression molded films ofthe copolymers prepared herein.

FIG. 7 is the tensile curves at up to 300% elongation of thecompression-molded films made from the copolymers produced usingcatalysts 37, 39 and 41 at reduced hydrogen loadings.

FIG. 8 is a graph of medium density component loading versus TMAloading.

FIG. 9 is a graph of lower density/medium density ratio versus TMAloading.

FIG. 10 is a graph of [HEH] triad loading versus TMA loading.

FIG. 11 is a graph of [HEH] mole fraction versus TMA (%) arranged byhydrogen content.

FIG. 12 is a graph of Mw/Mn versus amount of unknown species.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of this invention and the claims thereto the newnumbering scheme for the Periodic Table Groups are used as in CHEMICALAND ENGINEERING NEWS, 1985, 63(5), pg. 27.

For the purposes of this invention and the claims thereto when a polymeris referred to as comprising an olefin, the olefin present in thepolymer is the polymerized form of the olefin. Likewise when catalystcomponents are described as comprising neutral stable forms of thecomponents, it is well understood by one of ordinary skill in the art,that the ionic form of the component is the form that reacts with themonomers to produce polymers. In addition, a reactor is any container(s)in which a chemical reaction occurs.

In the description herein the transition metal compound may be describedas a catalyst precursor, a pre-catalyst compound, or a catalystcompound, and these terms are used interchangeably. A catalyst system iscombination of a catalyst precursor an activator, optional co-activatorand optional support. Preferred catalyst systems useful herein include acatalyst compound, methylalumoxane, trimethylaluminum and an optionalsupport.

For the purposes of this invention and the claims thereto, wt % isweight percent, Me is methyl, Pr is propyl, n-Pr is normal propyl, Ph isphenyl, TMA is trimethylaluminum, MAO is methylalumoxane, and Cp iscyclopentadienyl. MD is machine direction and TD is transversedirection. As used herein, the terms “low density polyethylene,” “LDPE,”“linear low density polyethylene,” and “LLDPE” refer to a polyethylenehomopolymer or copolymer having a density from 0.910 to 0.945 g/cm³. Theterms “polyethylene” and “ethylene polymer” mean a polyolefin comprisingat least 50 mole % ethylene units. Preferably, the “polyethylene” and“ethylene polymer” comprise at least 60 mole %, preferably at least 70mole %, preferably at least 80 mole %, even preferably at least 90 mole%, even preferably at least 95 mole %, or preferably 100 mole % ethyleneunits; and preferably have less than 15 mole % propylene units. An“ethylene elastomer” is an ethylene copolymer having a density of lessthan 0.86 g/cm³. An “ethylene plastomer” (or simply a “plastomer”) is anethylene copolymer having a density of 0.86 to less than 0.91 g/cm³. A“high density polyethylene” (“HDPE”) is an ethylene polymer having adensity of more than 0.945 g/cm³ or more. Polymers having more than twotypes of monomers, such as terpolymers, are also included within theterm “copolymer” as used herein. The terms “polypropylene” and“propylene polymer” mean a polyolefin comprising at least 50 mole %propylene units.

Peak Melting Point (Tm), heat of fusion (Hf), peak crystallization point(Tc) and heat of crystallization (Hc) are determined by DSC as describedbelow in the Examples section.

Unless otherwise stated, molecular weight distribution (“MWD”) isM_(w)/M_(n). Measurements of weight average molecular weight (M_(w)),number average molecular weight (M_(n)), and z average molecular weight(Mz) are determined by Gel Permeation Chromatography as described in theExamples section below.

Melt index (MI) and high load melt index (HLMI) are determined accordingto ASTM 1238 (190° C., 2.16 (I-2) or 21.6 kg (I-21), respectively). Meltindex ratio (MIR) is determined according to ASTM 1238 and is the ratioof HLMI to MI (e.g., I-21/I-2). In the event a weight is not specifiedas part of a melt index, it is assumed that 2.16 kg was used. Density isdetermined using chips cut from plaques compression molded in accordancewith ASTM D-4703-07 and aged for 40 hrs at 23° C. plus or minus 2° C.and measured as specified by ASTM D-1505, unless otherwise stated.Tensile properties, including Youngs modulus, tensile strength, stress,ultimate tensile stress, strain, ultimate strain, stress at 100%elongation, stress at 300% elongation, stress at the primary yieldpoint, and stress at the secondary yield point, 1% and 2% Secant Modulusare determined according to by ASTM D-882, except that the compressionmolded films were prepared as described below in the Examples section.Dart Impact is determined according to ASTM D-1709, method A. ElmendorfTear (MD and TD) is determined according to ASTM D-1922. Intrinsic tearis measured on a compression molded sheet using the Elmendorf tear (typeB) method as described in ASTM D-1922.

¹³C NMR spectroscopic analysis is conducted as follows: Polymer samplesfor ¹³C NMR spectroscopy are dissolved in d₂-1,1,2,2-tetrachloroethaneat concentrations between 10-15 weight percent prior to being insertedinto the spectrometer magnet. ¹³C NMR data is collected at 120° C. in a10 mm probe using a Varian spectrometer with a ¹Hydrogen frequency of700 MHz. A 90 degree pulse, an acquisition time adjusted to give adigital resolution between 0.1 and 0.12 Hz, at least a 10 second pulseacquisition delay time with continuous broadband proton decoupling usingswept square wave modulation without gating, is employed during theentire acquisition period. The spectra is acquired using time averagingto provide a signal to noise level adequate to measure the signals ofinterest. ¹³C NMR Chemical Shift Assignments and calculations involvedin characterizing polymers are made as outlined in the work of M. R.Seger and G. Maciel, “Quantitative ¹³C NMR Analysis of SequenceDistributions in Poly(ethylene-co-1-hexene)”, 2004, Anal. Chem., Vol.76, pp. 5734-5747; J. C. Randall, “Polymer Sequence Determination:Carbon-13 NMR Method” Academic Press, New York, 1977; and K. L. Koenig“Chemical Microstructure of Polymer Chains,” Robert E. KriegerPublishing Company, Florida 1990. For example, triad concentrations inethylene hexene copolymers are determined by spectral integration andnormalized to give the mole fraction of each triad:ethylene-ethylene-ethylene (EEE), ethylene-ethylene-hexene (EEH),ethylene-hexene-ethylene (EHE), hexene-ethylene-ethylene (HEE),hexene-ethylene-hexene (HEH), hexene-hexene-hexene (HHH). The observedtriad concentrations are converted into the following diadconcentrations: ethylene-ethylene (EE), hexene-hexene (HH) andethylene-hexene (EH). The diad concentrations are determined by thefollowing equations, where A represents one monomer and B the other.

[AA]=[AAA]+[AAB]/2

[AB]=2*[ABA]+[BBA]

The diad concentrations are then used to establish r₁r₂ as follows:

${r_{1}r_{2}} = {4*\frac{{EE}*{HH}}{({EH})^{2}}}$

Mole percent 1-hexene (Mole % comonomer) is determined as follows:

Mole Percent Hexene=(HHH+HHE+EHE)*100

Run Number is determined as follows:

Run Number=(HEH+½*HEE)*100

Average ethylene run length is calculated by dividing the comonomercontent by the run number. Average Ethylene RunLength=(HEH+EEH+EEE)/(run number).

“Butyls” per 1000 carbons is calculated by dividing the1-hexene-centered triads by the sum of twice the ethylene-centeredtriads plus six times the 1-hexene-centered triads and the resultantquotient multiplying by 1000.

${{Butyls}\mspace{14mu} {per}\mspace{14mu} 1000\mspace{14mu} {Carbons}} = {\frac{{HHH} + {HHE} + {EHE}}{{6*\left( {{HHH} + {HHE} + {EHE}} \right)} + {2\left( {{HEH} + {EEH} + {EEE}} \right)}}*1000}$

In ethylene copolymers where the comonomer is not hexene, the sameprocedure as above is employed and the H in the above examples wouldrepresent the comonomer. For example, in an ethylene-butene copolymerthe H would represent the butene monomer, in an ethylene-octenecopolymer the H would represent the octene monomer, etc. Likewise, insituations where there is more than one comonomer, then the H in theformulae above would represent all the comonomers. Further, when makingcomparisons of the copolymers produced herein to a random copolymer, aBernoullian distribution is used to represent the random copolymer asset out in K. L. Koenig “Chemical Microstructure of Polymer Chains”,Robert E. Krieger Publishing Company, Florida 1990.

Proton (¹H) NMR data is collected at 120° C. in a 5 mm probe using aVarian Spectrometer with a ¹Hydrogen frequency of at least 400 MHz. Thedata is recorded using a maximum pulse width of 45 degrees, 8 secondsbetween pulses and signal averaging 120 transients.

Preparative TREF (Temperature Rising Elution Fractionation)fractionation of the polymers in the example section below was performedby PolymerChar, Valencia Spain. PolymerChar's procedure used acommercial preparative TREF instrument (Model MC2, Polymer Char S. A.)to fractionate the resin into Chemical Composition Fractions. Thisprocedure employs a sequential TREF separation. Approximately 1 gram ofresin is dissolved in 100 ml of xylene, stabilized with 600 ppm ofbutylated hydroxy toluene (BHT), at 130° C. for one hour. The solutionis crystallized by slowly cooling it down to 30° C. or to subambienttemperatures using a cooling rate of 0.2° C. The cooled sample is heatedat its lowest temperature (30° C. or to subambient temperatures) for 45minutes and then the first fraction (the most amorphous) is collectedinto an external bottle, the rest of the polymer remains in the vesselas it has been retained by the filter. Subsequent fractions are obtainedby increasing the temperature stepwise, by about 3° C. per step, towithin a specified temperature range (such as a peak temperature),heated within that specified temperature range for 45 minutes andrepeating the same isolation procedure as for the first fraction. Onceall the fractions are isolated in the external bottles, the polymer isprecipitated by adding acetone and cooling the bottles. Then the mixtureis filtered using an external filtration system and recovering thephysical fractionated polymer.

Polymer Products

The process of this invention produces olefin polymers, preferablypolyethylene and polypropylene homopolymers and copolymers. In apreferred embodiment, the polymers produced herein are homopolymers ofethylene or propylene, are copolymers of ethylene preferably having from0 to 25 mole % (alternately from 0.5 to 20 mole %, alternately from 1 to15 mole %, preferably from 3 to 10 mole %) of one or more C₃ to C₂₀olefin comonomer (preferably C₃ to C₁₂ alpha-olefin, preferablypropylene, butene, hexene, octene, decene, dodecene, preferablypropylene, butene, hexene, octene), or are copolymers of propylenepreferably having from 0 to 25 mole % (alternately from 0.5 to 20 mole%, alternately from 1 to 15 mole %, preferably from 3 to 10 mole %) ofone or more of C₂ or C₄ to C₂₀ olefin comonomer (preferably ethylene orC₄ to C₁₂ alpha-olefin, preferably ethylene, butene, hexene, octene,decene, dodecene, preferably ethylene, butene, hexene, octene).

In a preferred embodiment, the monomer is ethylene and the comonomer ishexene, preferably from 1 to 15 mole % hexene, alternately 1 to 10 mole%.

Typically, the polymers produced herein have an Mw of 5,000 to 1,000,000g/mol (preferably 25,000 to 750,000 g/mol, preferably 50,000 to 500,000g/mol), and/or an Mw/Mn of greater than 1 to 40 (alternately 1.2 to 20,alternately 1.3 to 10, alternately 1.4 to 5, 1.5 to 4, alternately 1.5to 3).

In a preferred embodiment, the polymers produced herein have a deviationfrom random of greater than 0 for the [EHE] mole fraction. Likewise, thepolymers produced herein have a deviation from random of greater than 0for the [HHH] mole fraction. Deviation from random is equal to theobserved mole fraction minus the value of the mole fraction for a randomcopolymer calculated using the Bernoullian distribution for randomcopolymers as set out in K. L. Koenig “Chemical Microstructure ofPolymer Chains”, Robert E. Krieger Publishing Company, Florida 1990,hereinafter referred to as “calculated random mole fraction”.

In a Bernoulli process, a completely random process, the probability ofobtaining a test result, called P(x), is given by the BinomialDistribution:

${P(n)} = {\frac{n!}{{x!}{\left( {n - x} \right)!}}\left( {1 - p} \right)^{({n - x})}(p)^{x}}$

where x is a particular test result obtained in set of evaluations (n)and p is the probability that of observing the result (x).

Application of the Binomial Distribution to determining the distributionof triads in a random copolymer requires x be the number of hexenemonomers in the triad, taking on the values of 0, 1, 2 or 3 ([EEE],[HEE], [HHE] and [EEE]), n equals three and p is the mole fraction ofhexene in the copolymer.

Application of the Binomial Distribution to determining the loading oftriads in a random copolymer having the same hexene mole fraction as thesample resins requires filling out the following table, where p equal tothe mole fraction of hexene in the resin.

x $\frac{3!}{{x!}{\left( {3 - x} \right)!}}$ (1 − p)^((3−x)) (p)^(x)P(x) EEE** 0 1 (1 − p)³ p⁰ P(EEE) = 1*(1 − p)³ p⁰ HEE** 1 3 (1 − p)² p¹P(HEE) = 1*(1 − p)² p¹ HHE** 2 3 (1 − p)¹ p² P(HHE) = 1*(1 − p)¹ p²HHH** 3 1 (1 − p)⁰ p³ P(HHH) = 1*(1 − p)⁰ p³ **unordered

The loading of the HEE** and HHE** triads are used to define the loadingof the triads with a specific monomer sequence: HEE, EHE, HHE and HEH.The results in the above table are used as shown in the following tableto define the loading of the specific sequence of triads in a randomcopolymer having mole fraction of hexene equal to p.

[HHH] P(HHH) [HHE] (⅔) * P(HHE) [EHE] (⅓) * P(HEE) [HEH] (⅓) * P(HHE)[EEH] (⅔) * P(HEE) [EEE] P(EEE)

The following Table 6 is reproduced from the Example section.

TABLE 6 ¹³C NMR Analysis of LGPR resins: Observed Triad Loading (MoleFraction) Catalyst Mole % H Mole % E HHH HHE EHE HEH HEE EEE 36 1.6 98.40.0001 0.0004 0.0156 0.0002 0.0311 0.9527 37 3.4 96.6 0.0006 0.00180.0323 0.0025 0.0615 0.9013 39 3.5 96.5 0.0003 0.0020 0.0331 0.00200.0636 0.8990 41 3.36 96.64 0.0002 0.0020 0.0318 0.0021 0.0612 0.9028 443.51 96.49 0.0003 0.0018 0.0335 0.0025 0.0635 0.8984 42 3.24 96.760.0003 0.0017 0.0309 0.0022 0.0585 0.9064 43 3.29 96.71 0.0000 0.00190.0313 0.0019 0.0601 0.9048 46 3.21 96.79 0.0003 0.0014 0.0309 0.00210.0586 0.9068 46 3.35 96.65 0.0003 0.0017 0.0318 0.0019 0.0616 0.9027 Y3.1 96.9 0.0000 0.0015 0.0289 0.0017 0.0574 0.9107 X 3.31 96.69 0.00040.0009 0.0254 0.0014 0.0488 0.9231

TABLE 6A Observed Triad Loading (Mole Fraction) without restricting thesequence of the monomers in the triad (unordered). Catalyst 36 37 39 4144 42 43 46 46 X Y HHH** 0.0001 0.0006 0.0003 0.0002 0.0003 0.00030.0000 0.0003 0.0003 0.0004 0.0000 HHE** 0.0006 0.0043 0.0040 0.00410.0043 0.0039 0.0038 0.0035 0.0036 0.0023 0.0032 HEE** 0.0467 0.09380.0967 0.0930 0.0970 0.0894 0.0914 0.0895 0.0934 0.0742 0.0863 EEE**0.9527 0.9013 0.8990 0.9028 0.8984 0.9064 0.9048 0.9068 0.9027 0.92310.9107 **unordered

The table below shows the results of applying the binomial distributionto determining the triad distributions of a random copolymer with thesame hexene mole fraction as the resins in the example, X and Y resins.

TABLE 6B Predicted Triad Loadings (Mole Fraction) for a random copolymerwith the indicated hexene content.{circumflex over ( )} Catalyst 36 3739 41 44 42 43 46 46 X Y Hexene Mole 0.0160 0.0340 0.0350 0.0336 0.03510.0324 0.0329 0.0321 0.0335 0.0331 0.0310 Fraction Triad Loading HHH0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.00000.0000 HHE 0.0005 0.0022 0.0024 0.0022 0.0024 0.0020 0.0021 0.00200.0022 0.0021 0.0019 EHE 0.0155 0.0317 0.0326 0.0314 0.0327 0.03030.0308 0.0301 0.0313 0.0309 0.0291 HEH 0.0003 0.0011 0.0012 0.00110.0012 0.0010 0.0010 0.0010 0.0011 0.0011 0.0009 HEE 0.0310 0.06350.0652 0.0628 0.0654 0.0607 0.0615 0.0601 0.0626 0.0619 0.0582 EEE0.9528 0.9014 0.8986 0.9025 0.8984 0.9059 0.9045 0.9068 0.9028 0.90400.9099 {circumflex over ( )}all calculations done in Excel ™ 2003 withexpression to 4 decimal places.

TABLE 6C Predicted Triad Loading (Mole Fraction) for a random copolymerwith the indicated Hexene content without restricting the sequence ofthe monomers in the triad (unordered).{circumflex over ( )} Catalyst 3637 39 41 44 42 43 46 46 X Y Hexene Mole 0.0160 0.0340 0.0350 0.03360.0351 0.0324 0.0329 0.0321 0.0335 0.0331 0.0310 Fraction Triad LoadingHHH** 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.00000.0000 0.0000 HHE** 0.0008 0.0034 0.0035 0.0033 0.0036 0.0030 0.00310.0030 0.0033 0.0032 0.0028 HEE** 0.0465 0.0952 0.0978 0.0941 0.09800.0910 0.0923 0.0902 0.0939 0.0928 0.0873 EEE** 0.9528 0.9014 0.89860.9025 0.8984 0.9059 0.9045 0.9068 0.9028 0.9040 0.9099 **unordered,{circumflex over ( )}all calculations done in Excel ™ 2003 withexpression to 4 decimal places.

The following tables report the deviation from random of the triadloadings for the example resins from those of a random copolymer withthe same hexene content.

TABLE 6D Deviation of the Observed Triad Loading from that of a randomcopolymer with same hexene content Catalyst 36 37 39 41 44 42 43 46 46 XY Hexene 0.0160 0.0340 0.0350 0.0336 0.0351 0.0324 0.0329 0.0321 0.03350.0331 0.0310 Mole Fraction Deviation from Random HHH 0.0001 0.00060.0003 0.0002 0.0003 0.0003 0.0000 0.0003 0.0003 0.0004 0.0000 HHE−0.0001 −0.0004 −0.0004 −0.0002 −0.0006 −0.0003 −0.0002 −0.0006 −0.0005−0.0012 −0.0004 EHE 0.0001 0.0006 0.0005 0.0004 0.0008 0.0006 0.00050.0008 0.0005 −0.0055 −0.0002 HEH −0.0001 0.0014 0.0008 0.0010 0.00130.0012 0.0009 0.0011 0.0008 0.0003 0.0008 HEE 0.0001 −0.0020 −0.0016−0.0016 −0.0019 −0.0022 −0.0014 −0.0015 −0.0010 −0.0131 −0.0008 EEE−0.0001 −0.0001 0.0004 0.0003 0.0000 0.0005 0.0003 0.0000 −0.0001 0.01910.0008 *Positive numbers indicate triad loadings greater than thatexpected for a random copolymer of similar hexene content.

TABLE 6E Deviation of the Observed Triad Loading from that of a randomcopolymer with same Hexene content without restricting the sequence ofthe monomers in the triad (unordered). Catalyst 36 37 39 41 44 42 43 4646 X Y Hexene 0.0160 0.0340 0.0350 0.0336 0.0351 0.0324 0.0329 0.03210.0335 0.0331 0.0310 Mole Fraction Triad Loading HHH 0.0001 0.00060.0003 0.0020 0.0003 0.0003 0.0000 0.0003 0.0003 0.0004 0.0000 HHE−0.0002 0.0009 0.0005 0.0008 0.0007 0.0009 0.0007 0.0005 0.0003 −0.00090.0004 HEE 0.0002 −0.0014 −0.0011 −0.0011 −0.0010 −0.0016 −0.0009−0.0007 −0.0005 −0.0186 −0.0010 EEE −0.0001 −0.0001 0.0004 0.0003 0.00000.0005 0.0003 0.0000 −0.0001 0.0191 0.0008 *Positive numbers indicatetriad loadings greater than that expected for a random copolymer ofsimilar Hexene content.

In another embodiment, for the polymers produced herein the deviationfrom random for the [EEE] fraction divided by mole % comonomer in thepolymer times 100 is less than 10, preferably less than 5, preferablyless than 3. Specifically, in a preferred embodiment, for the polymersproduced herein the ((observed [EEE] triad fraction minus the calculatedrandom [EEE] fraction) divided by mole % hexene in the polymer *100) isless than 10, preferably less than 5, preferably less than 3 (whereE=ethylene).

In another preferred embodiment, the polymers produced herein have an[HHE]** mole fraction of greater than 0.005%, preferably greater than0.006%, preferably greater than 0.007%, where E=ethylene, and H iscomonomer, preferably hexene.

In a preferred embodiment, the polymers prepared herein have:

1) a Youngs Modulus of at least 215 MPa (alternately at least 230 MPa,alternately at least 260 MPa); and/or2) a 1% Secant Modulus of 30 to 100 MPa (alternately 35 to 90 MPa,alternately 40 to 85 MPa); and/or3) a 2% Secant Modulus of at least 100 MPa (alternately at least 101MPa, alternately at least 102 MPa); and/or4) an Ultimate Tensile Strain to Ultimate Tensile Stress ratio of about15 or more (preferably 20 or more, preferably 21 or more); and/or5) a tensile strength of at least Y MPa (alternately at least 17 MPa,alternately at least 18 MPa, alternately at least 19 MPa), whereY=(0.041)*Z−3.02 and Z is the percent strain (also referred to as thepercent elongation) and is a number from 500 to 2000, preferably 500 to1000, preferably 500, 550, 600, 650, 700, 800, 850, 900, 950, or 1000,preferably 500. Alternately, Y=(0.041)*Z−3.5. Alternately,Y=(0.041)*Z−4.0; and/or6) a density of 0.910 to 0.945 g/cc (preferably from 0.920 to 0.940g/cc, preferably from 0.921 to 0.935 g/cc, preferably from 0.917 to0.918 g/cc).

Particularly useful ethylene copolymers (including those described inthe preceding paragraph), such as ethylene-butene, ethylene-hexene,and/or ethylene-octene copolymers, prepared herein, preferably have:

1) an [HHH] triad content of 0.0005 mole % or more (preferably 0.0006mole % or more) where H is the comonomer (preferably butene, hexene oroctene, preferably hexene); and/or2) an r₁r₂ value of 0.85 or more (alternately 0.94 or more, alternately1.27 or more); and/or3) “butyls” per 1000 carbons of 12 or more (alternately 15 or more,alternately 16 or more); and/or4) a run number of 2.6 or more (alternately 3.0 or more, alternately 3.4or more); and/or5) an average ethylene run length of 0.27 or more (alternately 0.28 ormore, alternately 0.29 or more). Preferably when such ethylenecopolymers (particularly ethylene-hexene copolymers) are formed intocompression molded films 3 mil thick, the films have one or more(preferably two or more, preferably three or more, preferably four ormore, preferably five or more, preferably six or more, preferably sevenor more, preferably eight or more, preferably all nine) of the followingproperties:

a) a Youngs Modulus of at least 215 MPa (alternately at least 230 MPa,alternately at least 260 MPa); and/or

b) a Tensile Stress at 100 percent Elongation of at least 10 MPa(alternately at least 11 MPa, alternately at least 12 MPa); and/or

c) a Tensile Stress of Y MPa or more, where Y=(0.0532)*Z−8.6733 and Z isthe percent strain and is a number from 500 to 2000, preferably from 500to 1000, preferably 500, 550, 600, 650, 700, 800, 850, 900, 950, or1000, preferably 500, alternately Y=(0.0532)*Z−9.0, alternatelyY=(0.0532)*Z−9.5; and/or

d) a ratio of tensile strength at break, in MPa, to tensile strength at100% Elongation, in MPa, of 2.4 or more (preferably 2.5 or more,preferably 2.9 or more); and/or

e) an Ultimate Tensile Stress of at least 30 MPa (alternately at least32 MPa, alternately at least 35 MPa); and/or

f) an Ultimate Tensile Strain of at least 750% (alternately at least760%, alternately at least 768%); and/or

g) a ratio of Ultimate Tensile Strain to Ultimate Tensile Stress ofabout 17 or more (alternately 20 or more, alternately 21 or more);and/or

h) a 1% Secant Modulus of 30 to 100 MPa (alternately 35 to 90 MPa,alternately 40 to 85 MPa); and/or

i) a density of 0.910 to 0.945 g/cc (preferably from 0.920 to 0.940g/cc, preferably from 0.921 to 0.935 g/cc, preferably from 0.917 to0.918 g/cc).

This invention also relates to a polyethylene having comonomer(preferably hexene) present at about 3.4 mole % or more, an [HHH] triadcontent of 0.0006 mole % or more, an r₁r₂ value of 1.27 or more,“butyls” per 1000 carbons of 16 or more, a run number of 3.3 or more(alternately 3.4 or more), an average ethylene run length of 0.29 ormore at a Mw of from about 10,000 to about 320,000 g/mol with anM_(w)/M_(n) of from 2.5 to about 4.0, (preferably a density of 0.910g/cm³ or more and/or a 1% secant modulus of 30 to 100 MPa) where whenthe copolymer is formed into a compression molded film 3 mil thick, thefilm has: a Youngs Modulus of at least 260 MPa, a Tensile Stress at 100percent Elongation of at least 12 MPa, a Tensile Stress of Y MPa ormore, where Y=(0.0532)*Z−8.6733 and Z is the percent strain and is anumber from 500 to 2000, preferably 500 to 1000, preferably 500, 550,600, 650, 700, 800, 850, 900, 950, or 1000, preferably 500, a ratio oftensile strength at break, in MPa, to tensile strength at 100%Elongation, in MPa, of 2.9 or more, an Ultimate Tensile Stress of atleast 35 MPa, an Ultimate Tensile Strain of at least 768%, and a ratioof Ultimate Tensile Strain to Ultimate Tensile Stress of about 21 ormore.

This invention also relates to polyethylene films having at least onelayer (preferably having multilayer polyethylene film having at leastthree layers) of the ethylene copolymer produced herein (preferablyhaving any combination of the above properties), said copolymer having:

1) a melt index of (2.16 kg, 190° C.) 0.1 g/10 min to about 1.5 g/10 min(alternately from 0.2 g/10 min to 1.2 g/10 min, alternately preferablyfrom 0.25 g/10 min to 1 g/10 min);2) a density of 0.910 to 0.945 g/cc (preferably from 0.920 to 0.940g/cc, preferably from 0.921 to 0.935 g/cc, preferably from 0.917 to0.918 g/cc);3) an Mw/Mn of greater than 1 to about 5 (preferably 1.5 to about 4,preferably 2 to 4, preferably 2.5 to 4);where each layer may be the same or different ethylene polymer; andwherein the film (when formed into a compression molded film) has:

a) a thickness of 70 to 100 microns (preferably 19 to 70 microns);and/or

b) a Youngs Modulus of at least 220 MPa, preferably of at least 240 MPa,more preferably of at least 260 MPa; and/or

c) a 1% Secant Modulus of 30 to 100 MPa, preferably of 35 to 90 MPa,more preferably of 40 to 85 MPa; and/or

d) a 2% Secant Modulus of at least 100 MPa; and/or

e) a Yield Stress of at least 12 MPa at an elongation of at least 10%strain, preferably of at least 25%, and more preferably of at least 70%;and/or

f) a Primary Yield Point of at least 12 MPa at an elongation of at least15% strain, preferably of at least 18%; and/or

g) a Secondary Yield Point of at least 12 MPa at an elongation of atleast 60% strain, preferably of at least 65%, and most preferably of atleast 66%; and/or

h) a Tensile Stress at 100% Elongation of at least 12 MPa; and/or

i) a Tensile Stress at 200% Elongation of at least 12 MPa; and/or

j) a Tensile Stress at 300% Elongation of at least 13 MPa and preferablyof at least 14 MPa; and/or

k) a Tensile Stress of Y MPa or more, where Y=(0.041)*Z−3.02, and Z isthe percent strain and is a number from 500 to 2000, preferably 500 to1000, preferably 500, 550, 600, 650, 700, 800, 850, 900, 950, or 1000,preferably 500 (Alternately Y=(0.041)*Z−3.5, alternatelyY=(0.041)*Z−4.0); and/or

1) a ratio of tensile strength at 500% elongation, in MPa, to tensilestrength at yield, in MPa, of 1.3 or more, preferably 1.4 or more;and/or

m) a ratio of tensile strength at 600% elongation, in MPa, to tensilestrength at yield, in MPa, of 1.7 or more, preferably 1.8 or more;and/or

n) a ratio of tensile strength at 700% elongation, in MPa, to tensilestrength at yield, in MPa, of 2.1 or more, preferably 2.2 or more,preferably 2.3 or more; and/or

o) a ratio of tensile strength at 800% elongation, in MPa, to tensilestrength at yield, in MPa, of 2.4 or more, preferably 2.5 or more,preferably 2.9 or more; and/or

p) a ratio of tensile strength at break, in MPa, to tensile strength at100% Elongation, in MPa, of 2.9 or more; and/or

q) a ratio of tensile strength at break, in MPa, to tensile strength at300% Elongation, in MPa, of 2.5 or more; and/or

r) a ratio of tensile strength at break, in MPa, to tensile strength atthe Primary Yield Point, in MPa, of 2.9 or more; and/or

s) an Ultimate Tensile Stress of at least 30 MPa, preferably of at least35 MPa; and/or

t) an Ultimate Tensile Strain of at least 700%, more preferably of atleast 750% and most preferably of at least 768%; and/or

u) an Ultimate Tensile Strain to Ultimate Tensile Stress ratio of about21 or more.

In another embodiment, the film may have any combination of propertiesa) to u) above, including 1 to 21 of the properties, particularly 1, 2,3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 20, or 21 ofproperties a) to u) above.

In a preferred embodiment, the ethylene polymer produced herein is anLLDPE (linear low density polyethylene) polymer having a density of0.910 to 0.945 g/cc (preferably 0.920 to 0.940 g/cc). Preferably theLLDPE is produced using a hafnium metallocene catalyst as describedbelow.

In another preferred embodiment, the ethylene copolymers (particularlythe ethylene-hexene copolymers) produced herein have: 1) a density inthe range of from 0.910 to 0.945 g/cm³, preferably in the range of from0.920 to 0.940 g/cm³, more preferably in the range of from 0.916 to0.917 g/cm³; 2) an Mw of from about 10,000 to about 500,000 g/mol,preferably from about 10,000 to about 3200,000 g/mol, preferably fromabout 20,000 to about 200,000 g/mol, or from about 25,000 to about150,000 g/mol; 3) an M_(w)/M_(n) of from about 1.5 to about 5,particularly from about 2.0 to about 4.0, preferably from about 3.0 toabout 4.0 or from about 2.5 to about 4.0; 4) a melt index of from about0.1 g/10 to about 1.5 g/10 min, preferably from about 0.2 to about 1.2g/10 min and most preferably from about 0.25 to about 1 g/10 min; and 5)a melting point of about 115° C. to about 125° C., preferably from 115°C. to about 120° C. In another preferred embodiment, the ethylenecopolymers (particularly the ethylene-hexene copolymers) produced hereinmay also have: 1) a content of [HHH] triads of more than 0.0001 mole %or more, preferably more than 0.0004 mole %, preferably 0.0006 mole % ormore; and/or 2) at least 1 mole % (preferably at least 3 mole %,preferably at least 7 mole %) comonomer (preferably C₃ to C₂₀, olefin,preferably C₄ to C₁₂ alpha-olefin, preferably hexene, octene, and/orbutene) as determined by ¹³C NMR; and/or 3) an r₁r₂ value of 1.0 or more(preferably greater than 1.1, preferably more than 1.2); and/or 4)“butyls” per 1000 carbons of 7 or more (preferably 12 or more,preferably 15 or more, preferably 16 or more); and/or 5) a run number of1.6 or more (preferably 2.6 or more, preferably 3.4 or more, preferably3.3 or more, preferably 3.4 or more); and/or 6) an average ethylene runlength of 0.28 or more (preferably 0.29 or more).

In some embodiments, the polymers produced herein (preferably the LLDPEpolymers) exhibit a Tm as measured by differential scanning calorimetry(“DSC”) of from 90° C. or more, preferably from 100° C. to 200° C.,alternately from about 90° C. to about 130° C.

In another embodiment, the polymers produced herein contain less than 5ppm hafnium, generally less than 2 ppm hafnium, preferably less than 1.5ppm hafnium, more preferably less than 1 ppm hafnium. In an embodiment,the polymer produced herein contains in the range of from about 0.01 ppmto about 2 ppm hafnium, preferably in the range of from about 0.01 ppmto about 1.5 ppm hafnium, more preferably in the range of from about0.01 ppm to 1 or less ppm hafnium, as determined using ICPES(Inductively Coupled Plasma Emission Spectrometry).

In another preferred embodiment, compression molded films of theethylene copolymers (particularly the ethylene-hexene copolymers)produced herein preferably have: 1) a thickness of 70 to 100 microns(preferably 19 to 70 microns); and/or 2) a Youngs Modulus of at least220 MPa, preferably of at least 240 MPa, more preferably of at least 260MPa; and/or 3) a 1% Secant Modulus of 30 to 1000 MPa, preferably of 35to 90 MPa, more preferably of 40 to 85 MPa; and/or 4) a 2% SecantModulus of at least 100 MPa; and/or 5) a Yield Stress of at least 12 MPaat an elongation of at least 10% strain, preferably of at least 25%, andmore preferably of at least 70%; and/or 6) a Primary Yield Point of atleast 12 MPa at an elongation of at least 15% strain, preferably of atleast 18%; and/or 7) a Secondary Yield Point of at least 12 MPa at anelongation of at least 60% strain, preferably of at least 65%, and mostpreferably of at least 66%; and/or 8) a Tensile Stress at 100%Elongation of at least 12 MPa; and/or 9) a Tensile Stress at 200%Elongation of at least 12 MPa; and/or 10) a Tensile Stress at 300%Elongation of at least 13 MPa and preferably of at least 14 MPa; and/or11) a Tensile Stress of Y MPa or more, where Y=(0.041)*Z−3.02 and Z isthe percent strain and is a number from 500 to 2000, preferably 500 to1000, preferably 500, 550, 600, 650, 700, 800, 850, 900, 950, or 1000,preferably 500 (alternately Y=(0.041)*Z−3.5, alternatelyY=(0.041)*Z−4.0); and/or 12) a ratio of tensile strength at 500%elongation, in MPa, to tensile strength at yield, in MPa, of 1.3 ormore, preferably 1.4 or more, preferably 1.6 or more; and/or 13) a ratioof tensile strength at 600% elongation, in MPa, to tensile strength atyield, in MPa, of 1.7 or more, preferably 1.8 or more, and/or 14) aratio of tensile strength at 700% elongation, in MPa, to tensilestrength at yield, in MPa, of 2.1 or more, preferably 2.2 or more,preferably 2.3 or more; and/or 15) a ratio of tensile strength at 800%elongation, in MPa, to tensile strength at yield, in MPa, of 2.4 ormore, preferably 2.5 or more, preferably 2.9 or more; and/or 16) a ratioof tensile strength at break, in MPa, to tensile strength at 100%Elongation, in MPa, of 2.9 or more; and/or 17) a ratio of tensilestrength at break, in MPa, to tensile strength at 300% Elongation, inMPa, of 2.5 or more; and/or 18) a ratio of tensile strength at break, inMPa, to tensile strength at the Primary Yield Point, in MPa, of 2.9 ormore; and/or 19) an Ultimate Tensile Stress of at least 30 MPa,preferably of at least 35 MPa; and/or 20) an Ultimate Tensile Strain ofat least 700%, more preferably of at least 750% and most preferably ofat least 768%; and/or 21) an Ultimate Tensile Strain to Ultimate TensileStress ratio of about 21 or more; and/or 22) a density of 0.910 to 0.945g/cc (preferably from 0.920 to 0.940 g/cc, preferably from 0.921 to0.935 g/cc, preferably from 0.917 to 0.918 g/cc).

In another embodiment, any of the copolymers produced herein may have atensile strength at yield of greater than 11 MPa; and/or an ultimateelongation of greater than 750%; and/or an Ultimate stress of less than40 MPa; and/or an Ultimate strain to Ultimate stress ratio of greaterthan 17; and/or a 1% secant modulus of 30 to 100 MPa; and/or anintrinsic tear of 300 g/mil or less. (Intrinsic tear is measured on thecompression molded sheet using the Elmendorf tear (type B) method asdescribed in ASTM D-1922.)

Process and Catalyst

It has been discovered herein that polymer microstructure,macrostructure, and film properties made from polymers produced anddescribed herein can be specifically influenced by varying the amountsof trimethylaluminum (TMA) in a catalyst system containingmethylalumoxane and metallocene transition metal compounds, preferablyHf. In particular, we have found that by reducing the amount of TMA in agiven system, preferably in addition to reducing the aluminum totransition metal ratio (preferably the Al/Hf ratio), one can favorablyinfluence the comonomer incorporation and/or physical properties such astoughness. Specifically, we have also found that one can favorablyinfluence the resin's polydispersity, intermolecular comonomer (such ashexene) distribution, the intramolecular comonomer (such as hexene)distribution, and the final film properties when the resin is convertedinto a film. Likewise, by altering the amount of an unknown species(presumably related to the TMA content in the MAO) one can alsoinfluence final polymer properties. This unknown species is detected inthe ¹H NMR spectra obtained of the methylalumoxane activator. Using themethod disclosed in Organometallics, 1998, Vol. 17, No. 10, pp.1941-1945 modified as described in the examples section below, threeAl-Me species are distinguishable. A first broad signal due tooligomeric MAO is identified (for example, at from −0.2 to −1.2 ppm inFIG. 1). A second signal due to THF-complexed TMA is identified withinthe broad MAO signal (for example, at about −0.9 ppm in FIG. 1) and athird smaller up-field peak is identified within the broad MAO signal(for example, at about −0.55 ppm in FIG. 1). This third peak is referredto herein as the unknown species, unknown peak, or the unknown formula.Representative ¹H NMR spectra illustrating these signals are shown inFIGS. 1 and 2. The proton shifts are assigned based on referencing theresidual downfield peak in deuterated THF as 3.58 ppm. While individualspectra may not resolve at the specific points shown in FIG. 1, thebroad MAO range will contain the downfield THF complexed TMA peak and anupfield unknown peak. The integration units are defined on the basis ofthe TMA peak are being normalized to 3.0.

Hence, in a preferred embodiment, a low aluminum to transition metalmolar ratio (preferably a low Al/Hf molar ratio) is useful herein, suchas an aluminum to transition metal molar ratio (preferably an Al/Hfmolar ratio) of 175 or less, preferably 155 or less, preferably 150 orless, preferably 125 or less. Alternately the Al/Hf ratio is from 75:1to 175:1, preferably 100:1 to 175:1.

Alternately, in a preferred embodiment, the unknown species is presentin the catalyst system (prior to being combined with any support) at0.10 to 1.0, preferably 0.10 to 0.65 integration units, as measured by¹H NMR.

Alternately, in a preferred embodiment, trimethylaluminum is present inthe catalyst system (prior to being combined with any support) at 6 to25 mole %, preferably 8 to 20 mole %, preferably 9 to 18 mole %, asmeasured by ¹H NMR.

In a particularly preferred embodiment, the low Al/Hf ratios are used incombination with TMA concentrations in the catalyst system (prior tobeing combined with any support) of 6 to 25 mole %, preferably 8 to 20mole %, preferably 9 to 18 mole %, as measured by ¹H NMR.

In a particularly preferred embodiment, an Al/Hf ratio of 175 or less(preferably 155 or less, preferably 150 or less, preferably 125 or less,preferably 115 or less, preferably 112 or less, preferably 110 or less(alternately the Al/Hf ratio is from 75:1 to 175:1, preferably 100:1 to175:1), is used in combination with: 1) an unknown species presence inthe catalyst system (prior to being combined with any support) at 0.10to 0.65 integration units; and 2) a TMA concentrations in the catalystsystem (prior to being combined with any support) of 6 to 25 mole %(preferably 8 to 20 mole %, preferably 9 to 18 mole %).

Varying the catalyst systems' composition, typically prior to depositionon the support, as described herein controls the intermolecular andintramolecular comonomer (preferably hexene) distributions in copolymers(preferably ethylene copolymers). Surprisingly, the copolymer's [HHH]triad content increases with an increase in the amount of anunidentified species detected by ¹H NMR (see FIGS. 1 and 2) in thecatalyst system prior to being deposited on silica.

Surprisingly, the polymer's polydispersity (Mw/Mn) increases with anincrease in the amount of an unidentified species detected by ¹H NMR inthe catalyst system prior to being deposited on a support, such assilica.

This invention also relates to a method to produce block copolymerscomprising adjusting, preferably adjusting on-line, the amount oftrimethyl aluminum in a methylalumoxane solution prior to use,preferably in a continuous process, as an activator to obtain comonomertriad [HHH] fractions in the different segments (also referred to asblocks) that differ by at least 5% relative to each other (preferably byat least 10%, preferably at least 15%, preferably at least 20%,preferably at least 30%, preferably at least 50%, preferably at least75%, preferably at least 100%, preferably at least 250%, preferably atleast 500%). Differences in segments are confirmed by subjecting thepolymer to preparative TREF (as set out below), selecting the TREFfraction corresponding to the Mw as measured by GPC for the wholepolymer, measuring the Mw, Mn, Mz, mole % comonomer, and triad fractions(such as [HHH] fraction) for the TREF fraction, then subjecting thepolymer fraction to acid etching (using nitric acid oxidation accordingto the procedure in P. Palmer and A. J. Cobbold, Makromol Chemie 74, pg.174-189 (1964), except that the sample is treated for 48 hours),measuring the Mw, Mn, Mz, mole % comonomer, and triad fractions (such as[HHH] fraction) for the acid treated TREF fraction, then comparing themeasuring the Mw, Mn, Mz mole % comonomer, and triad fractions (such as[HHH] fraction) for the TREF fraction of the untreated fraction to theacid treated fraction.

The hexene distribution in the polymers made with lower Hf loading andlower TMA content is blockier, as evidenced by a [HHH] triad contentthat is twice that of a reference resin (see catalyst 39 in the Examplesection) and an r1r2 value (1.27) greater than that of the referenceresin (1.04).

The polymers produced herein also have a different distribution of TREFfractions corresponding to high, medium and low density components withpeak elute temperatures occurring at temperatures of 68° C. to 70° C.,84° C., and 90° C., respectively (see the Example section andPreparative TREF description for more information on how to obtain theTREF fractions).

It has also been discovered that decreasing the catalyst system'shafnium loading increases the amount of lower density component in thepolymer.

FIG. 3 shows the ratio of the wt %'s of the lower density component(peak elute temperatures occurring at temperatures of 68° C. to 70° C.)to higher density component (peak elute temperatures occurring attemperatures of 90° C.) components in the resins increases with adecrease in the Al/Hf ratio employed.

Likewise, it has been noted that decreasing the TMA loading decreasedthe wt % of the medium density materials in the product resins. Forexample, the exceptionally high loading of the medium density materialsin the Resin 42 (see Example section below) was surprising, see FIG. 8.Resin 36 in FIG. 8 was produced at the start of the campaign and thus isthought to have been produced in an unstable system, perhaps with muchlower hexene and/or hydrogen concentration. Thus, in another embodiment,the polymer produced herein has a content of Medium Density Component(wt %, based upon the weight of the whole polymer) less than or equal to0.3918 *(TMA loading wt %, based upon the weight of the solvent,catalyst compound and TMA)+16.722.

Likewise, it has been noted that decreasing the TMA loading increasedthe amount of lower density materials in resins. (See FIG. 9.) Thus, inanother embodiment, ratio of loading of Lower Density Component toMedium Density Component (wt %, based upon the weight of the wholepolymer) is greater than or equal to −0.067 *(TMA Loading wt %, basedupon the weight of the solvent, catalyst compound and TMA)+4.152.

It has also been noted that the mole % [HHH] triad in the polymerincreases with an increase in the amount of the unknown species—in thecatalyst system prior to contact with the support, as determined by ¹HNMR. This relationship can be represented by the equation: HHH TriadLoading (in mole fraction) is greater than or equal to 0.0014 *(UnknownPeak in Integration units)−0.0002.

It has also been noted that the polymer's [HEH] triad loading increaseswith a decrease in the catalyst's TMA loading. (See FIG. 10.)

It has also been noted that the polymer's Mw/Mn decreases with anincrease in the amount of the unknown species in the catalyst systemprior to combination with a support, as determined by ¹H NMR. Thisrelationship can be represented by the equation:

Mw/Mn≦−2.0508*(Unknown Peak in Integration units)+4.9873. (See FIG. 12.)

The inventors have also noted that the film performance (specificallythe tear resistance and impact resistance) of ethylene copolymersproduced according to the process described herein can be improved bydecreasing the amount of TMA in the catalyst system. See the Exampleswhich show reduced TMA to about to 2.4 percent by weight.

This invention relates to a process for polymerizing olefins in whichthe amount of trimethylaluminum in a methylalumoxane solution isadjusted to be from 1 to 25 mole % (preferably 6 to 25 mole %,preferably 8 to 20 mole %, preferably 9 to 18 mole %), prior to use asan activator, where the mole % TMA is determined by ¹H NMR of thesolution prior to combination with any support.

Alternately, this invention relates to a process for polymerizingolefins in which the amount of trimethylaluminum in catalyst systemcomprising methylalumoxane and a metallocene transition metal compoundsis adjusted to be from 6 to 25 mole % (preferably 8 to 20 mole %,preferably 9 to 18 mole %), prior to use as an activator, where the mole% TMA is determined by ¹H NMR of the catalyst system prior tocombination with any support.

In another embodiment, this invention relates to a process forpolymerizing olefins in which the amount of an unknown species presentin a methylalumoxane solution is adjusted to be from 0.10 to 1.0integration units (preferably 0.10 to 0.85 integration units, preferably0.10 to 0.65 integration units), prior to use as an activator, where theamount of unknown species is determined by ¹H NMR of the solutionperformed prior to combination with any support.

In another embodiment, this invention relates to a process forpolymerizing olefins in which the amount of an unknown species presentin catalyst system comprising methylalumoxane solution and a metallocenetransition metal compounds, is adjusted to be from 0.10 to 1.0integration units (preferably 0.10 to 0.85 integration units, preferably0.10 to 0.65 integration units), prior to use as an activator, where theamount of unknown species is determined by ¹H NMR of the solutionperformed prior to combination with any support.

Thus, in another preferred embodiment, this invention relates to aprocess to control comonomer distribution (such as [HHH] triaddistribution) comprising:

1) contacting a catalyst compound represented by the formula:

Cp ^(A) Cp ^(B)HfX*_(n)

wherein each X* and each Cp group is chemically bonded to Hf; n is 0, 1,2, 3, or 4; X* is a leaving group (such as an alkyl or a halide); Cp^(A)and Cp^(B) may be the same or different cyclopentadienyl ligands orligands isolobal to cyclopentadienyl, either or both of which maycontain heteroatoms and either or both of which may be substituted withmethylalumoxane and trimethylaluminum to form a catalyst system havingan Al/Hf ratio of 175 or less and 6 to 25 mole % trimethylaluminum,where when the catalyst system, prior to being combined with a support,is subjected to ¹H NMR a peak representing the unknown species ispresent in an amount of 0.10 to 1.0 integration units (preferably 0.10to 0.65 integration units);2) optionally combining the catalyst system with a support;3) contacting the catalyst system with two or more different olefins(e.g., differ by at least one carbon); and4) obtaining polymer.

In another embodiment, this invention relates to the use of TMAconcentration to control for technical effect, specifically ofcontrolling comonomer distribution and volume of TREF fractions elutingat 84° C., 90° C., and 68° C. to 70° C.

In another embodiment, the above can be used in a continuous system,where, prior to introduction into a polymerization reactor, the catalystsystem is tested to determine TMA content and/or unknown peak amount,and/or Al/Hf ratio, and thereafter the composition of the catalystsystem is altered prior to injection into a polymerization reactor.

In another embodiment, the above can be used in a continuous system,where, prior to introduction into a polymerization reactor, the catalystsystem is tested to determine

TMA content and/or unknown peak amount, and/or Al/Hf ratio, andthereafter the composition of the catalyst system is altered toinfluence polymer properties.

In another embodiment, the above can be used in a continuous system,where, a polymer exiting a reactor is tested to determine a property,such as comonomer distribution or volume of TREF fractions eluting at84° C., 90° C., and 68° C. to 70° C., and then the TMA content and/orunknown peak amount is altered (typically in the MAO solution or thecatalyst system), prior to introduction into a polymerization reactor.

To determine what levels of TMA are desirable for a specific system orpolymer, one may perform standard polymerizations, as follows. To begin,a solution of alumoxane (such as methyl alumoxane), 30 wt % in toluene,is prepared and the aluminum alkyl (such as TMA in the case of MAO) isremoved from the solution (for example, by combination withtrimethylphenol and filtration of the solid). Thereafter the metallocenecatalyst compound of interest is added (hereinafter “Solution A”).Thereafter multiple supported catalyst systems comprising metallocene,alumoxane, and aluminum alkyl (e.g., MAO and TMA) are prepared fromSolution A. The first supported catalyst system is prepared by addingenough aluminum alkyl to an aliquot of Solution A to make a supportedcatalyst having 0.5 mole % aluminum alkyl present in the catalyst systemprior to addition to the support. The next supported catalyst systemsare prepared by adding enough aluminum alkyl to an aliquot of Solution Ato make a catalyst system having 1.0 mole % aluminum alkyl present inthe catalyst system prior to supportation, and so on, progressing by 0.5mole % increments to 50 mole % aluminum alkyl present in the catalystsystem prior to supportation. It is important that the solutions areprepared and dried in the same manner to prepare the supported catalystsystem. The supported catalyst systems (including a supported SolutionA) are then each introduced into a polymerization reactor with theolefin monomers of interest (such as ethylene and 10 mole % hexene),keeping in mind that the catalyst system delivery method, polymerizationconditions, monomer concentrations, hydrogen concentrations (and allother concentrations of materials present in the polymerization), andquench conditions should be the same. The polymers produced are thentested for a property of interest. The property is then graphed versusthe mole % aluminum alkyl (mole % aluminum alkyl on the abscissa andproperty on the ordinate) to select the desired TMA levels for a givensystem. The same method can be used for the level of unknown species ina system.

Adjustment of the amount of alkyl aluminum (typically TMA) in thealumoxane solution or catalyst system can be achieved by adding orremoving (“removing” is defined to include preventing the TMA frominfluencing the polymerization, not just physically removing the TMA)alkyl aluminum (preferably TMA) to or from the catalyst system. Onemeans to remove alkyl aluminum (preferably TMA) is to contact thesolution with an alcohol (such as triphenyl methanol) and then filterthe solids from the solution. This is typically done with the alumoxanesolution prior to addition of the catalyst compound. For example, onewould begin with a solution of alumoxane (such as methyl alumoxane(MAO), typically obtained from Albemarle), 30 wt % in toluene.Generally, commercially available MAO contains some level of TMA. TheTMA level in a sample can be increased by addition of measured amount ofneat TMA (Aldrich, 99%). The TMA level is decreased by the reaction oforiginal MAO with a measured amount of Ph₃COH, followed by filtration ofthe white precipitate (which is thought to be some complex of Ph₃COHwith TMA, assuming that one molecule of Ph₃COH removes one molecule ofTMA). The solid is insoluble in toluene and is typically filtered fromthe MAO solution before using in supportation. The wt % of TMA as totalAluminum-methyl species in MAO solutions can be quantitativelydetermined by ¹H NMR (see Donald W. Imhoff, Larry S. Simeral, Samuel A.Sangokoya, and James H. Peel, Organometallics, 1998, No. 17, pp.1941-1945).

Alternately, adjustment of the amount of alkyl aluminum (typically TMA)available to influence the polymerization in the alumoxane solution orcatalyst system can be achieved by adding one or more Bronsted acids tothe solution. Useful Bronsted acids include phenolics, amines,phosphites, and the like, which are often used as antioxidants inpolymer production and processing. Preferred Bronsted acids includehindered phenolics, such as IRGANOX™ 1010 or IRGANOX™ 1076 (availablefrom Ciba-Geigy); phosphites (e.g., IRGAFOS™ 168 available fromCiba-Geigy); alkali metal and glycerol stearates; anti-static agents,and the like. Particularly useful Bronsted acids include: butylatedhydroxy toluene, tris(2,4-di-tert-butylphenyl)phosphite (IRGAFOS168),di(2,4-di-tert-butylphenyl)pentaerithritol diphosphite (ULTRANOX 626),poly[2-N,N′-di(2,2,6,6-tetramethyl-4-piperidinyl)-hexanediamine-4-(1-amino-1,1,3,3-tetramethylbutane)symtriazine](CHIMASORB 944); bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate (TINUVIN770), pentaerythrityl tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (IRGANOX 1010); Octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate (IRGANOX 1076); and1,3,5-Tri(3,5-di-tert-butyl-4-hydroxybenzyl-isocyanurate (IRGANOX 3114).

The Bronsted acids may be present in any effective amounts, such as0.001 to 10 wt %, alternately 0.005 to 2 wt %, based upon the weight ofthe catalyst/MAO/TMA solution entering the reactor.

In a preferred embodiment, the TMA is added intermittently to themethylalumoxane solution before or after combination with a catalystcompound, preferably the TMA is adjusted by adding a Bronsted Acid tothe methylalumoxane solution before or after combination with a catalystcompound.

The inventors have found that altering the amount of TMA present (oravailable to influence the polymerization) can alter the comonomerconcentration and distribution in the polymer product.

In another embodiment, this invention relates to a method to altercomposition distribution in a copolymer “on-line” by altering the amountof alkyl aluminum coactivator present on the supported catalyst system.

In a particularly preferred embodiment, the amount of the unknown peakin the catalyst system prior to supportation is altered by adding orsubtracting TMA.

In a preferred embodiment, in the above processes, the polymerizationprocess is a gas phase or slurry phase process.

Catalyst

Catalysts, useful herein, include a metallocene transition metalcompounds, which are defined to be transition metal (preferably group 4)compounds represented by the formula:

L ₂ MX_(n)

where M is a transition metal, preferably a group 4, 5, or 6 metal,preferably a group 4 metal, preferably Hf, Zr, or Ti; X is a leavinggroup (such as halogen or alkyl, such as chloride or methyl); and each Lgroup is a heteroatom containing group, or a substituted orunsubstituted cyclopentadienyl, indenyl or fluorenyl group, preferablyboth L groups are the same or different substituted or unsubstitutedcyclopentadienyl, indenyl or fluorenyl group.

Suitable catalysts for making the polymers described herein (preferablyLLDPE polymers) include hafnium transition metal metallocene-typecatalyst systems for polymerizing one or more olefins represented by theformula:

Cp ^(A) Cp ^(B)HfX*_(n)

wherein each X* is chemically bonded to Hf; X* is a leaving group (suchas a C₁ to C₄₀ hydrocarbyl or halide, preferably methyl, ethyl, propyl,butyl, chloride and bromide); each Cp group is chemically bonded to Hf;and n is 0, 1, 2, 3, or 4. Preferably, n is 1 or 2. The ligandsrepresented by Cp^(A) and Cp^(B) may be the same or differentcyclopentadienyl ligands or ligands isolobal to cyclopentadienyl, eitheror both of which may contain heteroatoms and either or both of which maybe substituted by a group R. In one embodiment, Cp^(A) and Cp^(B) areindependently selected from the group consisting of cyclopentadienyl,indenyl, tetrahydroindenyl, fluorenyl, and substituted derivatives ofeach.

Independently, each Cp^(A) and Cp^(B) may be unsubstituted orsubstituted with any one or combination of substituent groups R.Non-limiting examples of substituent groups R include hydrogen radicals,alkyls, alkenyls, alkynyls, cycloalkyls, aryls, acyls, aroyls, alkoxys,aryloxys, alkylthiols, dialkylamines, alkylamidos, alkoxycarbonyls,aryloxycarbonyls, carbomoyls, alkyl- and dialkyl-carbamoyls, acyloxys,acylaminos, aroylaminos, and combinations thereof. Particularlypreferred Cp^(A) and Cp^(B) groups may, independently, ben-propylcyclopentadienyl, n-butyl-cyclopentadienyl,n-hexyl-cyclopentadienyl, n-octyl-cyclopentadienyl,n-decyl-cyclopentadienyl, n-dodecyl-cyclopentadienyl, (CpMe_(x)PrH_(y),where x+y=4), (CpMe₄Pr), (Cpn-BuMeH₃), (CpPrMeH₃), (CpPrMe₃H), whereCp=cyclopentadienyl, Me=methyl, =Pr=propyl, and n-Bu is n-butyl.Preferred Cp^(A) and Cp^(B) groups may, independently, be n-alkyl-Cp,where the “n-alkyl” is preferably a C₂ to C₁₂ alkyl, preferably propyl,butyl, hexyl, octyl, decyl, or dodecyl.

In a particularly preferred embodiment, both Cp^(A) and Cp^(B) aresubstitute with an alkyl group (preferably an n-propyl group) at anyposition on the ring. A particularly preferred catalyst compound, usefulherein, is a bis(n-C₃₋₄ alkyl cyclopentadienyl) hafnium dialkyl ordihalide, preferably bis(n-propyl cyclopentadienyl) hafnium dichlorideor bis(n-propyl cyclopentadienyl) hafnium dimethyl.

In particularly preferred embodiments, both Cp^(A) and Cp^(B) arebridged via a bridging group A, where A is selected from R′₂C, R′₂Si,R′₂Ge, R′₂CCR′₂, R′₂CCR′₂CR′₂, R′C═CR′, R′C═CR′CR′₂, R′₂CSiR′₂,R′₂SiSiR′₂, R′₂CSiR′₂CR′₂, R′₂SiCR′₂SiR′₂, R′C═CR′SiR′₂, R′₂CGeR′₂,R′₂GeGeR′₂, R′₂CGeR′₂CR′₂, R′₂GeCR′₂GeR′₂, R′₂SiGeR′₂, R′C═CR′GeR′₂,R′B, R′₂C—BR′, R′₂C—BR′—CR′₂, R′N, R′₂C—NR′, R′₂C—NR′—CR′₂, R′P,R′₂C—PR′, and R′₂C—PR′—CR′₂ where R′ is, independently, hydrogen,hydrocarbyl (preferably C₁ to C₁₂ alkyl or C₁ to C₁₂ aryl), substitutedhydrocarbyl, halocarbyl, substituted halocarbyl, silylcarbyl, orgermylcarbyl, and two or more R′ on the same atom or on adjacent atomsmay join together to form a substituted or unsubstituted, saturated,partially unsaturated, or aromatic cyclic or polycyclic substituent;preferably A is one of the compounds listed as “Y” in Table 1 (beginningat column 23) of U.S. Pat. No. 7,276,567, more preferably A is selectedfrom the group consisting of dimethylsilylene, diethylsilylene,dipropylsilylene, diphenylsilylene, dimethylgermylene, diethylgermylene,diphenylgermylene, methylene, dimethylmethylene, diethylmethylene,dibutylmethylene, dipropylmethylene, diphenylmethylene,ditolylmethylene, di(butylphenyl)methylene,di(trimethylsilylphenyl)-methylene, di(trimethylsilylphenyl)-silylene,di(triethylsilylphenyl)-methylene, di(triethylsilylphenyl)-silylene,dibenzylsilylene, and dibenzylmethylene. Even more preferably, A isselected from dimethylsilylene, di(trimethylsilylphenyl)-methylene,dialkylgermylene, dialkylsilylene (where the alkyl is a C₂ to C₄₀substituted or unsubstituted alkyl group), cycloalkylsilyl, andcycloalkylsilyl (where the cycloalkyl is a C₂ to C₄₀ substituted orunsubstituted cycloalkyl group).

Exemplary hafnocene catalyst systems used to produce LLDPEs(particularly the ethylene-hexene copolymers), useful herein, are setforth in the description and examples of U.S. Pat. Nos. 6,936,675 and6,528,597, both of which are fully incorporated herein by reference.Particularly preferred catalysts include bis(n-propyl cyclopentadienyl)hafnium di-halide (preferably bromide, chloride or fluoride, alternatelypreferably chloride or fluoride, preferably fluoride). Additionallyuseful catalysts include bis(n-propyl cyclopentadienyl) hafniumdi-halide di-alkyl (preferably methyl, ethyl, or propyl). In someembodiments the dialkyl group is converted to a dihalide prior to use asa polymerization catalyst.

In a preferred embodiment, the polyethylene prepared herein is producedby polymerization of ethylene and, optionally, an alpha-olefin(preferably hexene) with a catalyst having as a transition metalcomponent a bis(n-C₃₋₄ alkyl cyclopentadienyl) hafnium compound (wherethe alkyl is preferably propyl or butyl), wherein the transition metalcomponent comprises from about 95 to about 99 mole % of the hafniumcompound.

The catalyst compounds described herein are used in combination with anactivator (such as alumoxane) and an aluminum alkyl co-activator (suchas triethylaluminum, tri-n-octyl aluminum, tri-isobutyl aluminum) withor without a trialkyl aluminum scavenger.

The catalyst compound combined with the activator and aluminum alkylco-activator is referred to as a catalyst system. Preferred alkylaluminums include dialkyl aluminums and trialkyl aluminums, preferablythose represented by the formulae: R₂ AlH and R₃Al, where each R isindependently a C₁ to C₂₀ alkyl group, preferably C₁ to C₁₂ alkyl group,preferably a C₁ to C₈ alkyl group, preferably methyl, ethyl, propyl,butyl, pentyl, hexyl, octyl, nonyl, decyl, undecyl, dodecyl, and isomersthereof (such as isopropyl or isobutyl). Aluminum alkyl ororgano-aluminum compounds, which may be utilized as co-activatorsherein, include trimethyl aluminum, triethyl aluminum, triisobutylaluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum, and the like. Aparticularly preferred alkyl aluminum is trimethyl aluminum. However, ifTMA is to be used as the scavenger, care should be taken to ascertainthe effects, if any, on the catalyst systems having specific TMAconcentrations disclosed herein.

In an alternate embodiment, the catalyst compounds disclosed herein areused with a second catalyst compound (such as those disclosed here),preferably in combination with a chain shuttling agent such asdiethylzinc.

In one embodiment, alumoxane activators are utilized as an activator inthe catalyst composition useful in the invention. An alumoxane isgenerally a mixture of both the linear and cyclic compounds. Alumoxanesare thought to be oligomeric compounds containing —Al(R¹)—O— sub-units,where R¹ is an alkyl group. Examples of alumoxanes include methylalumoxane (MAO), modified methyl alumoxane (MMAO), ethylalumoxane andisobutyl alumoxane. Alkylalumoxanes and modified alkyl alumoxanes aresuitable as catalyst activators, particularly when the abstractableligand is a halide, alkoxide or amide. Mixtures of different alumoxanesand modified alumoxanes may also be used.

Alumoxanes useful herein include those represented by the followingformulae:

(R³—Al—O)_(p)

and

R⁴(R⁵—Al—O)_(p)—AlR⁶ ₂

where R³, R⁴, R⁵, and R⁶ are, independently a C₁-C₃₀ alkyl radical, forexample, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,nonyl, decyl; and “p” is an integer from 1 to about 50. Most preferably,R³, R⁴, R⁵, and R⁶ are each methyl; and “p” is a least 4. When an alkylaluminum halide or alkoxide is employed in the preparation of thealumoxane, one or more R³⁻⁶ groups may be halide or alkoxide.

It is recognized that alumoxane is not a discrete material. A typicalalumoxane will contain free trisubstituted or trialkyl aluminum, boundtrisubstituted or trialkyl aluminum, and alumoxane molecules of varyingdegree of oligomerization. The methyl alumoxanes most preferred tend tocontain lower levels of trimethyl aluminum. Lower levels oftrimethylaluminum can be achieved by reaction of the trimethylaluminumwith a Lewis base or by vacuum distillation of the trimethylaluminum orby any other means known in the art.

When the activator is an alumoxane (modified or unmodified), someembodiments select the maximum amount of activator at a 5000-fold molarexcess Al/M over the catalyst precursor (per metal catalytic site). Theminimum activator-to-catalyst-precursor is a 1:1 molar ratio.

Alumoxanes may be produced by the hydrolysis of the respective trialkylaluminum compound. MMAO may be produced by the hydrolysis oftrimethylaluminum and a higher trialkyl aluminum such as triisobutylaluminum. MMAO's are generally more soluble in aliphatic solvents andmore stable during storage. There are a variety of methods for preparingalumoxane and modified alumoxanes, non-limiting examples of which aredescribed in U.S. Pat. Nos. 4,665,208; 4,952,540; 5,091,352; 5,206,199;5,204,419; 4,874,734; 4,924,018; 4,908,463; 4,968,827; 5,308,815;5,329,032; 5,248,801; 5,235,081; 5,157,137; 5,103,031; 5,391,793;5,391,529; 5,693,838; 5,731,253; 5,731,451; 5,744,656; 5,847,177;5,854,166; 5,856,256; and 5,939,346; European Publications EP-A-0 561476, EP-B1-0 279 586, EP-A-0 594-218, and EP-B1-0 586 665; and PCTPublications WO 94/10180 and WO 99/15534; all of which are herein fullyincorporated by reference. It may be preferable to use a visually clearmethylalumoxane. A cloudy or gelled alumoxane can be filtered to producea clear solution or clear alumoxane can be decanted from the cloudysolution. Another useful alumoxane is a modified methyl alumoxane (MMAO)cocatalyst type 3A (commercially available from Akzo Chemicals, Inc.under the trade name Modified Methylalumoxane type 3A, covered underU.S. Pat. No. 5,041,584).

The alumoxane/trialkyl aluminum activator combination may also be usewith a non-coordinating anion. Particularly useful NCA's includeN,N-dimethylanilinium tetrakisperfluorophenylborate, triphenylmethyltetrakisperfluorophenylborate, N,N-dimethylaniliniumtetrakisperfluoronapthylborate and the like, including the activatorsdescribed in U.S. Pat. No. 5,198,401. Further useful activator/catalystcombinations include NCA's and metallocenes on support as described inU.S. Pat. Nos. 6,040,261; 5,427,991; 5,869,723; and 5,643,847; and EP824,112.

In a preferred embodiment the catalyst, activator and coactivator aresupported on an inorganic oxide, such as silica, fumed silica and thelike. A preferred silica is one having an average particle size of 10 to100 microns, preferably 20 to 50 microns, preferably 20 to 35 microns. Auseful silica is available from Ineos Silicas, England under thetradename INEOS™ ES757. A preferred combination is MAO/(n-C₃Cp)₂Hf—X₂(where X₂ is di-halide or di-alkyl, preferably methyl, ethyl, propyl,butyl, bromide, chloride or fluoride) on silica, preferably dimethyl onsilica or difluoride on silica. The silica may be dried or calcinedprior to placing the catalyst, activator and co-activator on thesupport. The catalyst, activator, and co-activator may be placed on thesupport in any order.

It is preferred that the support material, most preferably an inorganicoxide, such as silica, has a surface area in the range of from about 10to about 700 m²/g, pore volume in the range of from about 0.1 to about4.0 cc/g, and average particle size in the range of from about 5 toabout 500 μm. More preferably, the surface area of the support materialis in the range of from about 50 to about 500 m²/g, pore volume of fromabout 0.5 to about 3.5 cc/g, and average particle size of from about 10to about 200 μm. Most preferably the surface area of the supportmaterial is in the range is from about 100 to about 400 m²/g, porevolume from about 0.8 to about 3.0 cc/g, and average particle size isfrom about 5 to about 100 μm. The average pore size of the carrieruseful in the invention typically has pore size in the range of from 10to 1000 Å, preferably 50 to about 500 Å, and most preferably 75 to about350 Å.

Further description of useful catalyst compounds are found in U.S. Pat.Nos. 6,242,545; 6,248,845; and 6,956,088; and in U.S. ApplicationPublication Nos. 2005/0171283 A1 and 2005/0215716 A1; all of which arefully incorporated herein by reference.

The hafnium transition metal metallocene-type catalyst compounds andcatalyst systems presently employed are suited for the polymerization ofmonomers, and, optionally, one or more comonomers, in any catalyticpolymerization process, solution phase, gas phase, or slurry phase.Preferably, a gas or slurry phase process is used. In particular, theprocess used to polymerize polymers (particularly LLDPE's) is asdescribed in the specification and examples of U.S. Pat. Nos. 6,936,675and 6,528,597, which are fully incorporated herein by reference.

In the processes used to manufacture the LLDPE's described herein, themonomer supplied to the polymerization zone is regulated to provide aratio of ethylene to alpha-olefin comonomer so as to yield apolyethylene having a comonomer content, as a bulk measurement, of fromabout 0.5 to about 25.0 mole % comonomer. The reaction temperature,monomer residence time, catalyst system component quantities, andmolecular weight control agent (such as H₂) may be regulated so as toprovide a LLDPE resin having a Mw from about 10,000 to about 500,000g/mol, and a MWD value of from about 1.0 to about 5. Specifically,comonomer to ethylene concentration or flow rate ratios are commonlyused to control resin density. Similarly, hydrogen to ethyleneconcentrations or flow rate ratios are commonly used to control resinmolecular weight. In both cases, higher levels of a modifier results inlower values of the respective resin parameter. Gas concentrations maybe measured by, for example, an on-line gas chromatograph or similarapparatus to ensure relatively constant composition of recycle gasstreams. One skilled in the art will be able to optimize these modifierratios and the given reactor conditions to achieve a targeted resin meltindex, density, and/or other resin properties. Additionally, the use ofa process continuity aid, while not required, may be desirable in any ofthe foregoing processes. Such continuity aids are well known to personsof skill in the art and include, for example, metal stearates(particularly calcium stearate).

One or more reactors in series or in parallel may be used in the presentinvention. Catalyst component, activator and co-activator may bedelivered as a suspension or slurry, activated in-line just prior to thereactor or preactivated and pumped as an activated suspension or slurryto the reactor. A preferred operation is two catalyst compounds orsystems activated in-line. For more information on methods to introducemultiple catalysts into reactors, please see U.S. Pat. No. 6,399,722,and WO 01/30862A1. While these references may emphasize gas phasereactors, the techniques described are equally applicable to other typesof reactors, including continuous stirred tank reactors, slurry loopreactors and the like. Polymerizations herein are carried out in eithersingle reactor operation, in which monomer, comonomers,catalyst/activator/co-activator, scavenger, and optional modifiers areadded continuously to a single reactor or in series reactor operation,in which the above components are added to each of two or more reactorsconnected in series. The catalyst components can be added to the firstreactor in the series and may also be added to both reactors, with onecomponent being added to first reaction and another component to otherreactors.

In one embodiment, 500 ppm or less of hydrogen is added to thepolymerization, or 400 ppm or less, or 300 ppm or less. In otherembodiments, at least 50 ppm of hydrogen is added to the polymerization,or 100 ppm or more, or 150 ppm or more.

In another embodiment, the polymerization process is run withscavengers, such as trimethyl aluminum, tri-isobutyl aluminum, and anexcess of alumoxane or modified alumoxane. However, if TMA is to be usedas the scavenger, care should be taken to ascertain the effects, if any,on the catalyst systems having specific TMA concentrations disclosedherein. Alternately, the process, preferably a slurry or gas phaseprocess, is operated in the absence of or essentially free of anyscavengers, such as triethylaluminum, trimethylaluminum,tri-isobutylaluminum, tri-n-hexyl aluminum, diethyl aluminum chloride,dibutyl zinc, and the like. This process is described in PCT PublicationWO 96/08520 and U.S. Pat. No. 5,712,352, which are herein fullyincorporated by reference.

Gas Phase Polymerization

The polymers described herein may be made in gas phase. Generally, in afluidized gas bed process used for producing polymers, a gaseous streamcontaining one or more monomers is continuously cycled through afluidized bed in the presence of a catalyst under reactive conditions.The gaseous stream is withdrawn from the fluidized bed and recycled backinto the reactor. Simultaneously, polymer product is withdrawn from thereactor and fresh monomer is added to replace the polymerized monomer.(See, for example, U.S. Pat. Nos. 4,543,399; 4,588,790; 5,028,670;5,317,036; 5,352,749; 5,405,922; 5,436,304; 5,453,471; 5,462,999;5,616,661; and 5,668,228; all of which are fully incorporated herein byreference.)

The reactor pressure in a gas phase process may vary from about 10 psig(69 kPa) to about 500 psig (3448 kPa), preferably from about 100 psig(690 kPa) to about 500 psig (3448 kPa), preferably in the range of fromabout 200 psig (1379 kPa) to about 400 psig (2759 kPa), more preferablyin the range of from about 250 psig (1724 kPa) to about 350 psig (2414kPa).

The reactor temperature in the gas phase process may vary from about 30°C. to about 120° C., preferably from about 60° C. to about 115° C., morepreferably in the range of from about 70° C. to 110° C., and mostpreferably in the range of from about 70° C. to about 95° C. In anotherembodiment, when higher density polyethylene is desired then the reactortemperature is typically between 70° C. and 105° C.

The productivity of the catalyst or catalyst system in a gas phasesystem is influenced by the partial pressure of the main monomer. Thepreferred mole % of the main monomer, ethylene, or propylene, preferablyethylene, is from about 25 to 90 mole % and the comonomer partialpressure is often in the range of from about 138 to about 2069 kPa,preferably about 517 to about 2069 kPa, which are typical conditions ina gas phase polymerization process. Also, in some systems the presenceof comonomer can increase productivity.

In a preferred embodiment, the catalyst system (preferably supported) isintroduced into a gas phase rector where the gas phase polymerizationoccurs at a temp of 70° C. to 105° C., a pressure of 690 to 2415 kPa,and is a continuous process preferably using a fluidized bed and arecycle stream as fluidizing medium.

In another preferred embodiment, the catalyst system (preferablysupported) is introduced into a gas phase rector where the gas phasepolymerization occurs at a temperature of 70° C. to less than 85° C.(preferably from 75° C. to 80° C.), an ethylene partial pressure of 105psi (0.72 MPa) or more (preferably 109 psi (0.75 MPa) or more,preferably 222 psi (1.53 MPa) or more, preferably 240 psi (1.66 MPa) ormore, preferably 260 psi (1.79 MPa) or more), and is a continuousprocess preferably using a fluidized bed and a recycle stream asfluidizing medium. In a particularly preferred process, the ethylenepartial pressure is greater than 30 mole %, alternately greater than 50mole %, alternately greater than 80 mole %, alternately greater than82.5 mole %. In another preferred embodiment, the ethylene partialpressure is 50 psi (345k Pa) to 250 psi (1724 kPa), preferably 100 psi(690 kPa) to 240 psi (1655 kPa). In another particularly preferredprocess, isopentane is used as a condensing agent.

Slurry Phase Polymerization

The polymers described herein may be made in slurry phase. A slurrypolymerization process generally operates between 1 to about 50atmosphere pressure range (15 psi to 735 psi (103 kPa to 5068 kPa)) oreven greater and temperatures in the range of 0° C. to about 120° C. Ina slurry polymerization, a suspension of solid, particulate polymer isformed in a liquid polymerization diluent medium to which monomer andcomonomers along with catalyst are added. The suspension includingdiluent is intermittently or continuously removed from the reactor wherethe volatile components are separated from the polymer and recycled,optionally after a distillation, to the reactor. The liquid diluentemployed in the polymerization medium is typically an alkane having from3 to 7 carbon atoms, preferably a branched alkane. The medium employedshould be liquid under the conditions of polymerization and relativelyinert. When a propane medium is used the process must be operated abovethe reaction diluent critical temperature and pressure. Preferably, ahexane or an isobutane medium is employed.

In one embodiment, a preferred polymerization technique useful in theinvention is referred to as a particle form polymerization, or a slurryprocess where the temperature is kept below the temperature at which thepolymer goes into solution. Such technique is well known in the art, anddescribed in for instance U.S. Pat. No. 3,248,179, which is fullyincorporated herein by reference. The preferred temperature in theparticle form process is within the range of about 85° C. to about 110°C. Two preferred polymerization methods for the slurry process are thoseemploying a loop reactor and those utilizing a plurality of stirredreactors in series, parallel, or combinations thereof. Non-limitingexamples of slurry processes include continuous loop or stirred tankprocesses. Also, other examples of slurry processes are described inU.S. Pat. No. 4,613,484, which is fully incorporated herein byreference.

In another embodiment, the slurry process is carried out continuously ina loop reactor. The catalyst, as a slurry in isobutane or as a dry freeflowing powder, is injected regularly to the reactor loop, which isitself filled with circulating slurry of growing polymer particles in adiluent of isobutane containing monomer and comonomer. Hydrogen,optionally, may be added as a molecular weight control. (In oneembodiment, 500 ppm or less of hydrogen is added, or 400 ppm or less, or300 ppm or less. In other embodiments, at least 50 ppm of hydrogen isadded, or 100 ppm or more, or 150 ppm or more.)

The reactor is maintained at a pressure of 3620 kPa to 4309 kPa and at atemperature in the range of about 60° C. to about 104° C. depending onthe desired polymer melting characteristics. Reaction heat is removedthrough the loop wall since much of the reactor is in the form of adouble-jacketed pipe. The slurry is allowed to exit the reactor atregular intervals or continuously to a heated low pressure flash vessel,rotary dryer, and a nitrogen purge column in sequence for removal of theisobutane diluent and all unreacted monomer and comonomers. Theresulting hydrocarbon free powder is then compounded for use in variousapplications.

In another embodiment, in the slurry process useful in the invention,the total reactor pressure is in the range of from 400 psig (2758 kPa)to 800 psig (5516 kPa), preferably 450 psig (3103 kPa) to about 700 psig(4827 kPa), more preferably 500 psig (3448 kPa) to about 650 psig (4482kPa), most preferably from about 525 psig (3620 kPa) to 625 psig (4309kPa).

In yet another embodiment, in the slurry process useful in theinvention, the concentration of predominant monomer in the reactorliquid medium is in the range of from about 1 to 10 wt %, preferablyfrom about 2 to about 7 wt %, more preferably from about 2.5 to about 6wt %, most preferably from about 3 to about 6 wt %.

Blends

In another embodiment, the polymer (preferably the polyethylene)produced herein is combined with one or more additional polymers priorto being formed into a film, molded part or other article. Other usefulpolymers include isotactic polypropylene, highly isotacticpolypropylene, syndiotactic polypropylene, random copolymer of propyleneand ethylene, and/or butene, and/or hexene, polybutene, ethylene vinylacetate, LDPE, LLDPE, HDPE, ethylene vinyl acetate, ethylene methylacrylate, copolymers of acrylic acid, polymethylmethacrylate or anyother polymers polymerizable by a high-pressure free radical process,polyvinylchloride, polybutene-1, isotactic polybutene, ABS resins,ethylene-propylene rubber (EPR), vulcanized EPR, EPDM, block copolymer,styrenic block copolymers, polyamides, polycarbonates, PET resins, crosslinked polyethylene, copolymers of ethylene and vinyl alcohol (EVOH),polymers of aromatic monomers such as polystyrene, poly-1 esters,polyacetal, polyvinylidine fluoride, polyethylene glycols, and/orpolyisobutylene.

Preferred ethylene-based polymer compositions also include blends of theethylene polymer (preferably a linear low density polyethylene) and oneor more additional polymers selected from the following: one or morevery low density polyethylenes, one or more low density polyethylenes,one or more medium density polyethylenes, one or more high densitypolyethylenes, one or more differentiated polyethylene, or otherconventional polymers.

In alternate embodiments, elastomers are blended with the polymer(preferably the LLDPE) produced herein to form rubber toughenedcompositions that are typically formed into films or molded parts. In aparticularly preferred embodiment, the rubber toughened composition is atwo (or more) phase system where the elastomer is a discontinuous phaseand the polymer produced by this invention is a continuous phase. Thisblend may be combined with tackifiers and/or other additives asdescribed herein.

In a preferred embodiment, the polymer (preferably the polyethylene) ispresent in the above blends, at from 10 to 99 wt %, based upon theweight of the polymers in the blend, preferably 20 to 95 wt %, even morepreferably at least 30 to 90 wt %, even more preferably at least 40 to90 wt %, even more preferably at least 50 to 90 wt %, even morepreferably at least 60 to 90 wt %, even more preferably at least 70 to90 wt %.

The blends described above may be produced by mixing the polymers of theinvention with one or more polymers (as described above), by connectingreactors together in series to make reactor blends or by using more thanone catalyst in the same reactor to produce multiple species of polymer.The polymers can be mixed together prior to being put into the extruderor may be mixed in an extruder.

The blends may be formed using conventional equipment and methods, suchas by dry blending the individual components and subsequently meltmixing in a mixer, or by mixing the components together directly in amixer, such as, for example, a Banbury mixer, a Haake mixer, a Brabenderinternal mixer, or a single or twin-screw extruder, which may include acompounding extruder and a side-arm extruder used directly downstream ofa polymerization process, which may include blending powders or pelletsof the resins at the hopper of the film extruder. Additionally,additives may be included in the blend, in one or more components of theblend, and/or in a product formed from the blend, such as a film, asdesired. Such additives are well known in the art, and can include, forexample: fillers; antioxidants (e.g., hindered phenolics such asIRGANOX™ 1010 or IRGANOX™ 1076 available from Ciba-Geigy); phosphites(e.g., IRGAFOS™ 168 available from Ciba-Geigy); anti-cling additives;tackifiers, such as polybutenes, terpene resins, aliphatic and aromatichydrocarbon resins, alkali metal and glycerol stearates, andhydrogenated rosins; UV stabilizers; heat stabilizers; anti-blockingagents; release agents; anti-static agents; pigments; colorants; dyes;waxes; silica; fillers; talc; and the like.

End-Use Applications

Specifically, any of the foregoing polymers, such as the foregoingpolyethylenes or blends thereof, may be used in a variety of end-useapplications. Such applications include, for example, mono- ormulti-layer blown, extruded, and/or shrink films. These films may beformed by any number of well known extrusion or coextrusion techniques,such as a blown bubble film processing technique, wherein thecomposition can be extruded in a molten state through an annular die andthen expanded to form a uni-axial or biaxial orientation melt prior tobeing cooled to form a tubular, blown film, which can then be axiallyslit and unfolded to form a flat film. Films may be subsequentlyunoriented, uniaxially oriented, or biaxially oriented to the same ordifferent extents. One or more of the layers of the film may be orientedin the transverse and/or longitudinal directions to the same ordifferent extents. The uniaxially orientation can be accomplished usingtypical cold drawing or hot drawing methods. Biaxial orientation can beaccomplished using tenter frame equipment or a double bubble processesand may occur before or after the individual layers are broughttogether. For example, a polyethylene layer can be extrusion coated orlaminated onto an oriented polypropylene layer or the polyethylene andpolypropylene can be coextruded together into a film then oriented.Likewise, oriented polypropylene could be laminated to orientedpolyethylene or oriented polyethylene could be coated onto polypropylenethen optionally the combination could be oriented even further.Typically the films are oriented in the Machine Direction (MD) at aratio of up to 15, preferably between 5 and 7, and in the TransverseDirection (TD) at a ratio of up to 15, preferably 7 to 9. However, inanother embodiment the film is oriented to the same extent in both theMD and TD directions.

In another embodiment, the layer comprising the polyethylene compositionof this invention (and/or blends thereof) may be combined with one ormore other layers. The other layer(s) may be any layer typicallyincluded in multilayer film structures. For example, the other layer orlayers may be: 1) Polyolefins: Preferred polyolefins includehomopolymers or copolymers of C₂ to C₄₀ olefins, preferably C₂ to C₂₀olefins, preferably a copolymer of an alpha-olefin and another olefin oralpha-olefin (ethylene is defined to be an alpha-olefin for purposes ofthis invention). Preferably, homopolyethylene, homopolypropylene,propylene copolymerized with ethylene, and/or butene, ethylenecopolymerized with one or more of propylene, butene, or hexene, andoptional dienes. Preferred examples include thermoplastic polymers, suchas ultra low density polyethylene, very low density polyethylene, linearlow density polyethylene, low density polyethylene, medium densitypolyethylene, high density polyethylene, polypropylene, isotacticpolypropylene, highly isotactic polypropylene, syndiotacticpolypropylene, random copolymer of propylene and ethylene, and/orbutene, and/or hexene, elastomers, such as ethylene propylene rubber,ethylene propylene diene monomer rubber, neoprene, and blends ofthermoplastic polymers and elastomers, such as, for example,thermoplastic elastomers and rubber toughened plastics. 2) Polarpolymers: Preferred polar polymers include homopolymers and copolymersof esters, amides, acetates, anhydrides, copolymers of a C₂ to C₂₀olefin, such as ethylene, and/or propylene, and/or butene with one ormore polar monomers, such as acetates, anhydrides, esters, alcohol,and/or acrylics. Preferred examples include polyesters, polyamides,ethylene vinyl acetate copolymers, and polyvinyl chloride. 3) Cationicpolymers: Preferred cationic polymers include polymers or copolymers ofgeminally disubstituted olefins, alpha-heteroatom olefins, and/orstyrenic monomers. Preferred geminally disubstituted olefins includeisobutylene, isopentene, isoheptene, isohexane, isooctene, isodecene,and isododecene. Preferred alpha-heteroatom olefins include vinyl etherand vinyl carbazole, preferred styrenic monomers include styrene, alkylstyrene, para-alkyl styrene, alpha-methyl styrene, chloro-styrene, andbromo-para-methyl styrene. Preferred examples of cationic polymersinclude butyl rubber, isobutylene copolymerized with para methylstyrene, polystyrene, and poly-alpha-methyl styrene. 4) Miscellaneous:Other useful layers can be paper, wood, cardboard, metal, metal foils(such as aluminum foil and tin foil), metallized surfaces, glass(including silicon oxide (SiO_(x)) coatings applied by evaporatingsilicon oxide onto a film surface), fabric, spunbonded fibers, andnon-wovens (particularly polypropylene spunbonded fibers or non-wovens),and substrates coated with inks, dyes, pigments, PVDC, and the like.

The films may vary in thickness depending on the intended application;however, films of a thickness from 1 to 50 μm are usually suitable.Films intended for packaging are usually from 10 to 50 μm thick. Thethickness of the sealing layer is typically 0.2 to 50 μm. There may be asealing layer on both the inner and outer surfaces of the film or thesealing layer may be present on only the inner or the outer surface.

In another embodiment, one or more layers may be modified by coronatreatment, electron beam irradiation, gamma irradiation, flametreatment, or microwave. In a preferred embodiment, one or both of thesurface layers is modified by corona treatment.

The films described herein may also comprise from 5 to 60 wt %, basedupon the weight of the polymer and the resin, of a hydrocarbon resin.The resin may be combined with the polymer of the outer (such as seal)layer(s) or may be combined with the polymer in the core layer(s).

The films described above may be used as stretch and/or cling films withor without common tackifying additives (such as polybutenes, terpeneresins, alkali metal stearates, and hydrogenated rosins and rosinesters), and/or modification by well-known physical processes (such ascorona discharge). Stretch/clings films may comprise a slip layercomprising any suitable polyolefin or combination of polyolefins such aspolyethylene, polypropylene, copolymers of ethylene and propylene, andpolymers obtained from ethylene, and/or propylene copolymerized withminor amounts of other olefins, particularly C₄ to C₁₂ olefins.Particularly preferred are polypropylene and linear low densitypolyethylene (LLDPE).

Multiple-layer films may be formed by methods well known in the art. Thetotal thickness of multilayer films may vary based upon the applicationdesired. A total film thickness of about 5 to 100 μm, more typicallyabout 10 to 50 μm, is suitable for most applications. Those skilled inthe art will appreciate that the thickness of individual layers formultilayer films may be adjusted based on desired end-use performance,resin, or copolymer employed, equipment capability, and other factors.The materials forming each layer may be coextruded through a coextrusionfeedblock and die assembly to yield a film with two or more layersadhered together but differing in composition.

When used in multilayer films, the LLDPE polymer blends are typicallyused in at least three layers and may be used in any layer of the film,as desired. When more than one layer of the film is formed of a LLDPEpolymer blend, each such layer can be individually formulated; i.e., thelayers formed of the LLDPE polymer blend can be the same or differentchemical composition, density, melt index, thickness, etc., dependingupon the desired properties of the film.

To facilitate discussion of different film structures, the followingnotation is used herein. Each layer of a film is denoted “A” or “B”,where “A” indicates a conventional film layer as defined below, and “B”indicates a film layer formed of any of the LLDPE polymers or blends.Where a film includes more than one A layer or more than one B layer,one or more prime symbols (′, ″, ′′, etc.) are appended to the A or Bsymbol to indicate layers of the same type (conventional or inventive)that can be the same or can differ in one or more properties, such aschemical composition, density, melt index, thickness, etc. Finally, thesymbols for adjacent layers are separated by a slash (/). Using thisnotation, a three-layer film having an inner layer of a LLDPE polymerblend disposed between two outer, conventional film layers would bedenoted A/B/A′. Similarly, a five-layer film of alternatingconventional/inventive layers would be denoted A/B/A′/B′/A″. Unlessotherwise indicated, the left-to-right or right-to-left order of layersdoes not matter, nor does the order of prime symbols; e.g., an A/B filmis equivalent to a B/A film, and an A/A′/B/A″ film is equivalent to anA/B/A′/A″ film. The relative thickness of each film layer is similarlydenoted, with the thickness of each layer relative to a total filmthickness of 100 (dimensionless) indicated numerically and separated byslashes; e.g., the relative thickness of an A/B/A′ film having A and A′layers of 10 μm each and a B layer of 30 μm is denoted as 20/60/20.

For the various films described herein, the “A” layer can be formed ofany material known in the art for use in multilayer films or infilm-coated products. Thus, for example, each A layer can be formed of apolyethylene homopolymer or copolymer, and the polyethylene can be, forexample, a VLDPE, a LDPE, a LLDPE, a MDPE, a HDPE, or a DPE, as well asother polyethylenes known in the art. The polyethylene can be producedby any suitable process, including metallocene-catalyzed processes andZiegler-Natta catalyzed processes. Further, each A layer can be a blendof two or more such polyethylenes, and can include additives known inthe art. Further, one skilled in the art will understand that the layersof a multilayer film must have the appropriate viscosity match.

In multilayer structures, one or more A layers can also be anadhesion-promoting tie layer, such as PRIMACOR™ ethylene-acrylic acidcopolymers available from The Dow Chemical Company, and/orethylene-vinyl acetate copolymers. Other materials for A layers can be,for example, foil, nylon, ethylene-vinyl alcohol copolymers,polyvinylidene chloride, polyethylene terephthalate, orientedpolypropylene, ethylene-vinyl acetate copolymers, ethylene-acrylic acidcopolymers, ethylene-methacrylic acid copolymers, graft modifiedpolymers, and paper.

The “B” layer is formed of a LLDPE polymer or blend, and can be any ofsuch blends described herein. In one embodiment, the B layer is formedof a blend of (a) from 0.1 to 99.9 wt % of a first polymer selected fromthe group consisting of very low density polyethylene, medium densitypolyethylene, differentiated polyethylene, and combinations thereof; and(b) from 99.9 to 0.1 wt % of a second polymer comprising a LLDPE polymeror copolymer produced by gas-phase polymerization of ethylene and,optionally, an alpha-olefin with a catalyst having as a transition metalcomponent a bis(n-C₃₋₄ alkyl cyclopentadienyl) hafnium compound, whereinthe transition metal component comprises from about 95 to about 99 mole% of the hafnium compound. The copolymer of (b) is preferablycharacterized by a comonomer content of up to about 5 mole %, a meltindex I_(2.16) of from about 0.1 to about 300 g/10 min, a melt indexratio of from about 15 to about 45, a weight average molecular weight offrom about 20,000 to about 200,000, a molecular weight distribution offrom about 2.0 to about 4.5, and a M_(z)/M_(w) ratio of from about 1.7to about 3.5. In preferred embodiments, the polymer of (a) is differentfrom the polymer of (b).

The thickness of each layer of the film, and of the overall film, is notparticularly limited, but is determined according to the desiredproperties of the film. Typical film layers have a thickness of fromabout 1 to about 1000 μm, more typically from about 5 to about 100 μm,and typical films have an overall thickness of from about 10 to about100 μm.

In further applications, microlayer technology may be used to producefilms with a large number of thinner layers. For example, microlayertechnology may be used to obtain films having, for example, 24, 50, or100 layers, in which the thickness of an individual layer is less than 1μm. Individual layer thicknesses for these films may be less than 0.5μm, less than 0.25 μm, or even less than 0.1 μm.

In other embodiments, using the nomenclature described above, multilayerfilms have any of the following exemplary structures: (a) two-layerfilms, such as A/B and B/B; (b) three-layer films, such as A/B/A′,A/A′/B, B/A/B′, and B/B′/B″; (c) four-layer films, such as A/A′/A″/B,A/A′/B/A″, A/A′/B/B′, A/B/A′/B′, A/B/B′/A′, B/A/A′/B′, A/B/B′/B″,B/A/B′/B″, and B/B′/B″/B′″; (d) five-layer films, such as A/A′/A″/A′″/B,A/A′/A″/B/A′″, A/A′/B/A″/A′″, A/A′/A″/B/B′, A/A′/B/A″/B′, A/A′/B/B′/A″,A/B/A′/B′/A″, A/B/A′/A″/B, B/A/A′/A″/B′, A/A′/B/B′/B″, A/B/A′/B′/B″,A/B/B′/B″/A′, B/A/A′/B′/B″, B/A/B′/A/B″, B/A/B′/B″/A′, A/B/B′/B″/B″′,B/A/B′/B″/B′″, B/B′/A/B″/B′″, and B/B′/B″/B″′/B″′; and similarstructures for films having six, seven, eight, nine, twenty-four,forty-eight, sixty-four, one hundred, or any other number of layers. Itshould be appreciated that films having still more layers can be formedusing the LLDPE polymers or blends, and such films are within the scopeof the invention.

In any of the embodiments above, one or more A layers can be replacedwith a substrate layer, such as glass, plastic, paper, metal, etc., orthe entire film can be coated or laminated onto a substrate. Thus,although the discussion herein has focused on multilayer films, thefilms composed of LLDPE polymer blends can also be used as coatings;e.g., films formed of the inventive polymers or polymer blends, ormultilayer films including one or more layers formed of the inventivepolymers or polymer blends, can be coated onto a substrate such aspaper, metal, glass, plastic, and other materials capable of accepting acoating. Such coated structures are also within the scope of the presentinvention.

In another aspect, provided are any polymer products containing theLLDPE polymer or polymer blend compositions produced by methods known inthe art. In addition, also included are products having other specificend-uses, such as film-based products, which include stretch films,shrink films, bags (i.e., shipping sacks, trash bags and liners,industrial liners, and produce bags), flexible and food packaging (e.g.,fresh cut produce packaging, frozen food packaging), personal carefilms, pouches, medical film products, diaper back sheets, and housewrap. Products may also include packaging, for example, by bundling,packaging and unitizing a variety of products. Applications for suchpackaging include various foodstuffs, rolls of carpet, liquidcontainers, and various like goods normally containerized and/orpalletized for shipping, storage, and/or display.

In some embodiments, stretch cling films may be formed from the LLDPEpolymers and polymer blends described herein. The stretch cling filmsmay be monolayer or multilayer, with one or more layers comprising theLLDPE polymers or blends. In some embodiments, the films may becoextruded, comprising one or more layers made from the LLDPE polymersor blends described herein, along with one or more layers of traditionalZiegler-Natta or metallocene-catalyzed LLDPE, which may, optionally,include a comonomer, such as, for example, hexene or octene.

Some resins and blends described herein may also be suited for use instretch hand wrap films. Stretch film hand wrap requires a combinationof excellent film toughness, especially puncture and dart dropperformance, and a very stiff, i.e., difficult to stretch, film. Thisfilm ‘stiffness’ is required to optimize the stretch required to provideadequate load holding force to a wrapped load and to prevent furtherstretching of the film. The film toughness is required because hand wraploads (being wrapped) are typically more irregular and frequentlycontain greater puncture requirements than typical machine stretchloads. In some embodiments, the films may be down gauged stretch handwrap films. In further embodiments, LLDPE resins and blends may beblended with LDPE, other LLDPEs, or other polymers to obtain a materialwith characteristics suitable for use in stretch hand wrap films.

Further product applications may also include surface protectionapplications, with or without stretching, such as in the temporaryprotection of surfaces during manufacturing, transportation, etc. Thereare many potential applications of articles and films produced from thepolymer blend compositions described herein.

The LLDPE resins and blends prepared as described herein are also suitedfor the manufacture of blown film in a high-stalk extrusion process. Inthis process, a polyethylene melt is fed through a gap (typically 1 to1.6 mm) in an annular die attached to an extruder and forms a tube ofmolten polymer which is moved vertically upward. The initial diameter ofthe molten tube is approximately the same as that of the annular die.Pressurized air is fed to the interior of the tube to maintain aconstant air volume inside the bubble. This air pressure results in arapid 3-to-9-fold increase of the tube diameter which occurs at a heightof approximately 5 to 10 times the die diameter above the exit point ofthe tube from the die. The increase in the tube diameter is accompaniedby a reduction of its wall thickness to a final value ranging fromapproximately 12.7 to 50 microns and by a development of biaxialorientation in the melt. The expanded molten tube is rapidly cooled(which induces crystallization of the polymer), collapsed between a pairof nip rolls and wound onto a film roll.

Two factors are useful to determine the suitability of a particularpolyethylene resin or blend for high stalk extrusion: the maximumattainable rate of film manufacture and mechanical properties of theformed film. Adequate processing stability is desired at, for example,throughput rates of up to 2.7 Kg/hr/cm die and high line speeds (>61m/min) for thin gauge manufacture on modern extrusion equipment. Personsof skill in the art will recognize that varying throughput rates andline speeds may be used without departing from the spirit of the presentinvention, and that the figures given herein are intended forillustrative purposes only. The resins and blends produced as describedherein have molecular characteristics which allow them to be processedsuccessfully at these high speeds. Mechanical strength of the film isdifferent in two film directions, along the film roll (machinedirection, MD) and in the perpendicular direction (transverse direction,TD). Typically, the TD strength in such films is significantly higherthan their MD strength. The films manufactured from the resins preparedin the process of this invention with the catalysts described hereinhave a favorable balance of the MD and TD strengths.

Films composed of LLDPE polymers or blends thereof show improvedperformance and mechanical properties when compared to films previouslyknown in the art. For example, films containing the LLDPE polymers andblends described herein have improved seal strength and hot tackperformance, increased toughness, and lower reblock. The films also havea good balance of stiffness vs. toughness as indicated by tear strength,1% Secant Modulus, and Dart Impact performance. In addition, such filmsmay also exhibit higher ultimate stretch and have better processabilitywhen compared with other LLDPE resins and blends.

In another embodiment this invention relates to:

1. A process for polymerizing olefins in which the amount oftrimethylaluminum in a methylalumoxane solution is adjusted to be from 1to 25 mole % (preferably 6 to 25 mole %), prior to use as an activator,where the mole % trimethylaluminum is determined by ¹H NMR of thesolution prior to combination with any support.2. A process for polymerizing olefins in which the amount of an unknownspecies present in a methylalumoxane solution is adjusted to be from0.10 to 0.65 integration units, prior to use as an activator, where theunknown species is identified in the ¹H NMR spectra of the solutionprior to combination with any support.3. The process of paragraph 1 or 2, wherein the methylalumoxane solutionis present in a catalyst system also comprising a metallocene transitionmetal compound.4. The process of paragraph 1 or 3, wherein the amount oftrimethylaluminum is adjusted by adding or removing trimethylaluminum,preferably by adding or removing TMA to or from the methylalumoxanesolution.5. The process of paragraph 2 or 3, wherein the amount of an unknownspecies is adjusted by adding or removing trimethylaluminum.6. The process of any of paragraphs 2 to 5, wherein the catalyst systemin methylalumoxane solution prior to combination with any support has analuminum to transition metal molar ratio (preferably an aluminum tohafnium molar ratio) of 175:1 or less, preferably 175:1 to 50:1.7. The process of any of paragraphs 2 to 6, wherein the metallocenetransition metal compound is represented by the formula:

Cp ^(A) C ^(B)HfX*_(n)

wherein each X* and each Cp group is chemically bonded to Hf, n is 1 or2, Cp^(A) and Cp^(B) may be the same or different cyclopentadienylligands or ligands isolobal to cyclopentadienyl, either or both of whichmay contain heteroatoms and either or both of which may be substituted.8. The process of paragraph 7, wherein Cp^(A) and Cp^(B) areindependently selected from the group consisting of cyclopentadienyl,indenyl, tetrahydroindenyl, fluorenyl, and substituted derivatives ofeach.9. The process of any of paragraphs 2 to 8, wherein the metallocenetransition metal compound comprises a bis(n-C₃₋₄ alkyl cyclopentadienyl)hafnium dialkyl or dihalide.10. The process of any of paragraphs 2 to 8, wherein the metallocenetransition metal compound comprises bis(n-propyl cyclopentadienyl)hafnium dichloride and/or bis(n-propyl cyclopentadienyl) hafniumdimethyl.11. The process to polymerize olefins of any of paragraphs 1 to 10,wherein the alumoxane solution is combined with a metallocene transitionmetal compound and with one or more olefins.12. The process of any of paragraphs 1 to 11, wherein the polymerizationprocess is a gas phase process.13. The process of paragraph 11 or 12, wherein the olefins compriseethylene and the ethylene partial pressure in the gas phasepolymerization is from 50 to 250 psi (345 to 1724 kPa).14. The process of any of paragraphs 1 to 11, wherein the polymerizationprocess is a slurry phase process.15. The process of any of paragraphs 1 to 14, wherein the olefinscomprise ethylene and at least one C₃ to C₂₀ olefin.16. The process of paragraph 15, wherein the C₃ to C₂₀ olefin is one ormore of propylene, butene, hexene, and octene.17. The process of paragraph 15, wherein the C₃ to C₂₀ olefin is hexene.18. A copolymer produced by any of paragraphs 1 to 17, wherein thepolymer produced is a copolymer comprising ethylene and from 0.5 to 25mole % of C₃ to C₂₀ olefin comonomer, said copolymer having: a tensilestress at the secondary yield point of 12 MPa or more; a ratio ofultimate tensile strain to ultimate tensile stress of 20 or more; atensile stress at 200% (MPa) that is greater than the tensile stress atthe at the secondary yield point (MPa); a comonomer triad ([HHH] triad)of 0.0005 mole % or more, preferably 0.0006 or more; a density of 0.910g/cm³ or more, and a 1% secant modulus of 30 to 100 MPa.19. A copolymer produced by any of paragraphs 1 to 17, wherein thepolymer produced is a copolymer comprising ethylene and from 0.5 to 25mole % of C₃ to C₂₀ olefin comonomer, said copolymer having: 1) a ratioof Ultimate Tensile Stress to Tensile Stress at 100% elongation of 2.5or more; 2) a ratio of Ultimate Tensile Stress to Tensile Stress at 300%elongation of 2.4 or more; 3) a ratio of Ultimate Tensile Stress toTensile Stress at the primary yield point of 2.9 or more; 4) a densityof 0.910 g/cm³ or more; 5) a 1% secant modulus of 30 to 100 MPa; and 6)a Tensile Stress of Y MPa or more, where Y=(0.0532)*Z−8.6733 and Z isthe percent strain and is a number from 500 to 2000.20. A copolymer comprising ethylene and from 0.5 to 25 mole % of C₃ toC₂₀ olefin comonomer, said copolymer having: a tensile stress at thesecondary yield point of 15 MPa or more; a ratio of ultimate tensilestrain to ultimate tensile stress of 19.9 or more; a tensile stress at200% (MPa) that is greater than the tensile stress at the at thesecondary yield point (MPa); a comonomer triad ([HHH] triad) of 0.0005mole % or more, preferably 0.0006 mole % or more; a density of 0.910g/cm³ or more; and a 1% secant modulus of 30 to 100 MPa.21. A copolymer comprising ethylene and from 0.5 to 25 mole % of C₃ toC₂₀ olefin comonomer, said copolymer having: 1) a ratio of UltimateTensile Stress to Tensile Stress at 100% elongation of 2.5 or more; 2) aratio of Ultimate Tensile Stress to Tensile Stress at 300% elongation of2.4 or more; 3) a ratio of Ultimate Tensile Stress to Tensile Stress atthe primary yield point of 2.9 or more; 4) a density of 0.910 g/cm³ ormore; 5) a 1% secant modulus of 30 to 100 MPa; and 6) a Tensile Stressof Y MPa or more, where Y=(0.0532)*Z−8.6733 and Z is the percent strainand is a number from 500 to 2000.22. The copolymer of any of paragraphs 18 to 21, wherein the copolymercomprises ethylene and from 0.5 to 25 mole % of hexene.23. The copolymer of paragraphs 18 to 21, wherein the copolymer has anMw of from 5000 to 1,000,000 g/mol.24. A film formed from the copolymers of any of paragraphs 18 to 23.25. A process to produce block copolymers comprising adjusting theamount of trimethyl aluminum in a methylalumoxane solution prior to useas an activator to obtain [HHH] fractions that differ by at least 5%relative to each other.26. The process of paragraph 25, wherein the process is a continuousprocess and the TMA is adjusted on-line prior to entry into apolymerization reactor.27. The process of paragraph 26, wherein the TMA is added intermittentlyto the methylalumoxane solution before or after combination with acatalyst compound.28. The process of any of paragraphs 1 to 18 or 25 to 27, wherein theTMA is adjusted by adding a Bronsted Acid to the methylalumoxanesolution before or after combination with a catalyst compound.29. The polymer produced by the process of any of paragraphs 1 to 18,25, 26, 27 or 28, or the polymer (or film thereof) of any of paragraphs19 to 24, wherein the deviation from random when the random [HHH] molefraction of the copolymer is subtracted from the measured random [HHH]mole fraction is greater than zero, and/or the deviation from randomwhen the random [EHE] mole fraction of the copolymer is subtracted fromthe measured random [EHE] mole fraction is greater than zero.30. The polymer produced by the process of any of paragraphs 1 to 18, 25to 29, or the polymer (or film thereof) of any of paragraphs 19 to 24,wherein the polymer has a tensile strength at yield of greater than 11MPa, and/or an ultimate elongation of greater than 750%, and/or anUltimate stress of less than 40 MPa, and/or an Ultimate strain toUltimate stress ratio of greater than 17, and/or a 1% secant modulus of30 to 100 MPa, and/or an intrinsic tear of 300 g/mil or less.31. An ethylene-C₄ to C₈ alpha olefin copolymer (preferably butene,hexene or octene) having from 0.5 to 25 mole % comonomer and a densityof 0.910 g/cm³ or more where the deviation from random when thecalculated random [HHH] mole fraction of the copolymer is subtractedfrom the measured [HHH] mole fraction is greater than zero, and/or thecalculated random [EHE] mole fraction of the copolymer is subtractedfrom the measured [EHE] mole fraction is greater than zero.

EXAMPLES Tests and Materials

Where applicable, the properties and descriptions below are intended toencompass measurements in both the machine and transverse directions.Such measurements are reported separately, with the designation “MD”indicating a measurement in the machine direction, and “TD” indicating ameasurement in the transverse direction. Elmendorf tear (tear) wasmeasured as specified by ASTM D-1922. Tensile properties, includingYoung's modulus, tensile strength, tensile stress, ultimate tensilestress, tensile strain, ultimate tensile strain, tensile stress at 100%(200%, 300%, 400%, 500%, 600%, 700%, 800%, etc.) elongation, stress andstrain at the primary yield point, stress and strain at the secondaryyield point, 1% and 2% Secant modulus, tensile strength at yield,tensile strength at break, ultimate tensile strength, elongation atyield, elongation at break, yield stress, and strain hardening weremeasured as specified by ASTM D-882. Melt index (MI) and high load meltindex (HLMI) were determined according to ASTM 1238 (190° C., 2.16 (I-2)or 21.6 kg (I-21), respectively). Melt index ratio (MIR) was determinedaccording to ASTM 1238 and is the ratio of HLMI to MI (e.g., I-21/I-2).In the event a weight is not specified as part of a melt index, it isassumed that 2.16 kg was used. Density was determined measured asspecified by ASTM D-1505 using chips cut from plaques compression moldedin accordance with ASTM D-4703-07, aged in for 40 hrs at 23° C. plus orminus 2° C., unless specifically stated otherwise. Dart prop (also knownas Dart F₅₀, or Dart prop Impact or Dart prop Impact Strength) wasmeasured as specified by ASTM D-1709, method A. Tm, Hf, Tc, and Hc weremeasured using the DSC procedure as follows: Samples weighingapproximately 5 to 10 mg were sealed in aluminum sample pans. The DSCdata were recorded by first cooling the sample to −50° C. and thengradually heating it to 200° C. at a rate of 10° C./minute. The samplewas kept at 200° C. for 5 minutes before a second cooling-heating cyclewas applied. Both the first and second cycle thermal events wererecorded. The melting temperature (Tm) and heat of fusion (Hf) weremeasured and reported during the second heating cycle (or second melt).The crystallization temperature (Tc) and heat of crystallization (Hc)were measured and reported during the first heating cycle (or firstmelt). Prior to the DSC measurement, the sample is aged (typically byholding it at ambient temperature for a period of 5 days) or annealed tomaximize the level of crystallinity.

CFC (Cross Fractionation Analysis) of the polymers below was performedby PolymerChar, Valencia Spain. PolymerChar's procedure used acommercial TREF instrument (Model MC2, Polymer Char S.A.) to fractionatethe resin into Chemical Composition Fractions and analyze the fractionusing GPC methodology. This procedure employs a sequential TREFseparation followed by a GPC analysis. Approximately 150 mg of sample isdissolved in 20 ml of o-DCB, then an aliquot of the solution (0.5 ml) isloaded in the instrument's column, crystallized and fractions byincreasing the temperature stepwise and using a fixed pump flow rate.Approximately 0.5 ml portions of the fractions coming out of the TREFfractionation at each temperature step are passed through a GPCcolumn(s) heated at 150° C. using a volumetric flow rate of 1 ml/min andthen through the infrared detector. GPC chromatograms of each fractionobtained from the TREF fractionation at each temperature step arerecorded. Approximately 43 GPC chromatograms are obtained per sample.These data were then grouped by peak elution temperature. The data arereported in Table 5.

The elements present in a sample are determined using ICPES (InductivelyCoupled Plasma Emission Spectrometry), which is described in J. W.Olesik, “Inductively Coupled Plasma-Optical Emission Spectroscopy,” inEncyclopedia of Materials Characterization, C. R. Brundle, C. A. Evans,Jr. and S. Wilson, eds., Butterworth-Heinemann, Boston, Mass., 1992, pp.633-644).

Molecular weight distribution (polydispersity) is Mw/Mn. Measurements ofweight average molecular weight (M_(w)), number average molecular weight(M_(n)), and z average molecular weight (Mz) are determined by GelPermeation Chromatography as described in Macromolecules, 2001, Vol. 34,No. 19, pg. 6812, which is fully incorporated herein by reference,including that, a High Temperature Size Exclusion Chromatograph (SEC,Waters Alliance 2000), equipped with a differential refractive indexdetector (DRI) equipped with three Polymer Laboratories PLgel 10 mmMixed-B columns is used. The instrument is operated with a flow rate of1.0 cm³/min, and an injection volume of 300 μL. The various transferlines, columns and differential refractometer (the DRI detector) arehoused in an oven maintained at 145° C. Polymer solutions are preparedby heating 0.75 to 1.5 mg/mL of polymer in filtered1,2,4-Trichlorobenzene (TCB) containing 1000 ppm of BHT at 160° C. for 2hours with continuous agitation. A sample of the polymer containingsolution is injected into to the GPC and eluted using filtered1,2,4-Trichlorobenzene (TCB) containing 1000 ppm of BHT. The separationefficiency of the column set is calibrated using a series of narrow MWDpolystyrene standards reflecting the expected MWD range of the samplebeing analyzed and the exclusion limits of the column set. Seventeenindividual polystyrene standards, obtained from Polymer Laboratories(Amherst, Mass.) and ranging from Peak Molecular Weight (Mp) ˜580 to10,000,000, were used to generate the calibration curve. The flow rateis calibrated for each run to give a common peak position for a flowrate marker (taken to be the positive inject peak) before determiningthe retention volume for each polystyrene standard. The flow marker peakposition is used to correct the flow rate when analyzing samples. Acalibration curve (log(Mp) vs. retention volume) is generated byrecording the retention volume at the peak in the DRI signal for each PSstandard, and fitting this data set to a 2nd-order polynomial. Theequivalent polyethylene molecular weights are determined by using theMark-Houwink coefficients shown in Table B.

TABLE B Mark-Houwink coefficients Material k (dL/g) A PS 1.75 × 10 −40.67 PE 5.79 × 10 −4 0.695

The ¹³C NMR spectroscopic analysis is conducted as follows: Polymersamples for ¹³C NMR spectroscopy are dissolved ind₂-1,1,2,2-tetrachloroethane at concentrations between 10 to 15 wt %prior to being inserted into the spectrometer magnet. ¹³C NMR data iscollected at 120° C. in a 10 mm probe using a Varian spectrometer with a¹Hydrogen frequency of 700 MHz. A 90° pulse, an acquisition timeadjusted to give a digital resolution between 0.1 and 0.12 Hz, at leasta 10 second pulse acquisition delay time with continuous broadbandproton decoupling using swept square wave modulation without gating isemployed during the entire acquisition period. The spectra is acquiredusing time averaging to provide a signal to noise level adequate tomeasure the signals of interest. ¹³C NMR Chemical Shift Assignments andcalculations involved in characterizing polymers are made as outlined inthe work of M. R. Seger and G. Maciel, “Quantitative ¹³C NMR Analysis ofSequence Distributions in Poly(ethylene-co-1-Hexene)”, Anal. Chem.,2004, 76, pp. 5734-5747. Triad concentrations are determined by spectralintegration and normalized to give the mole fraction of each triad:ethylene-ethylene-ethylene (EEE), ethylene-ethylene-Hexene (EEH),ethylene-Hexene-ethylene (EHE), Hexene-ethylene-ethylene (HEE),Hexene-ethylene-Hexene (HEH), Hexene-Hexene-Hexene (HHH). The observedtriad concentrations are converted into the following diadconcentrations: ethylene-ethylene (EE), Hexene-Hexene (HH) andethylene-Hexene (EH). The diad concentrations are determined by thefollowing equations, where A represents one monomer and B the other.

[AA]=[AAA]+[AAB]/2

[AB]=2*[ABA]+[BBA]

The diad concentrations are then used to establish r₁r₂ as follows:

${r_{1}r_{2}} = {4*\frac{{EE}*{HH}}{({EH})^{2}}}$

Mole percent 1-Hexene (Mole % comonomer) is determined as follows:

Mole Percent Hexene=(HHH+HHE+EHE)*100

Run Number is determined as follows:

Run Number=(HEH+½*HEE)*100

Average ethylene run length is calculated by dividing the comonomercontent by the run number.

Average Ethylene Run Length=(HEH+EEH+EEE)/(run number).

“Butyls” per 1000 carbons is calculated by dividing the1-Hexene-centered triads by the sum of twice the ethylene-centeredtriads plus six times the 1-Hexene-centered triads and the resultantquotient multiplying by 1000.

${{Butyls}\mspace{14mu} {per}\mspace{14mu} 1000\mspace{14mu} {Carbons}} = {\frac{{HHH} + {HHE} + {EHE}}{{6*\left( {{HHH} + {HHE} + {EHE}} \right)} + {2\left( {{HEH} + {EEH} + {EEE}} \right)}}*1000}$

Proton ¹H NMR data for polymer characterization collected at 120° C. ina 5 mm probe using a Varian Spectrometer with a ¹Hydrogen frequency of400 MHz. The data was recorded using a maximum pulse width of 45degrees, 8 seconds between pulses, and signal averaging 120 transientsin solvent of C₂D₂Cl₄.

The Proton ¹H NMR data for alumoxane solution characterization wasobtained using the method (normalization approach) described atOrganometallics, 1998, Vol. 17, No. 10, pp. 1941-1945, except that aSpectrometer with a ‘Hydrogen frequency of 250 MHz (Brukner DPX 250Instrument with Bruker XWIN-NMR version 2.1 software) was used. Spectrawere obtained at 120° C. using a 5 mm probe, and the data were recordedusing a maximum pulse width of 45 degrees, 8 seconds between pulses andsignal averaging 120 transients. The proton shifts were assigned basedon referencing the residual downfield peak in deuterated THF as 3.58 ppm(99.9% deuterated). The integration units were defined on the basis ofthe TMA peak being normalized to 3.0.

Specifically, MAO samples (30 wt % in toluene) were dissolved in THF-d8at least 5:1 by volume and spectra taken on a Bruker 250 MHz instrument.Three Al-Me species could be distinguished, the very broad signal due tooligomeric MAO from −0.2 to −1.2 ppm (OAl-Me)_(x) which has the averageformula (O_(0.8)AlMe_(1.3))_(x), the THF-complexed TMA at −0.9 and asmaller upfield peak around −0.55 of unknown formula. The relativeamount of the unknown species was also determined and reported in Table2. The amount of unknown species was found to be inversely proportionalto the TMA level.

The supported bis(n-propylcyclopentadienyl)hafnium dimethyl/MAO/TMAcatalyst systems used herein were prepared frombis(n-propylcyclopentadienyl) hafnium dimethyl purchased from BoulderScientific, Colorado, USA; Ineos ™ES757 microsphereoidal silica having a25 micron average particle size (INEOS); methylalumoxane (30 wt % intoluene, said MAO having approximately 15 wt % trimethylaluminum, e.g.,4.5 wt % of solution received is TMA) purchased from Albemarle; andtrimethyl aluminum, reagent grade purchased from Aldrich. The MAO intoluene purchased from Albemarle was sometimes used as received,sometimes combined with Ph₃COH then filtered to remove solids, and wassometimes spiked with TMA. Catalysts were made by reacting the MAOsolutions diluted with additional toluene with (Cp-nPr)₂HfMe₂ at roomtemperature for 0.5 hrs. ES 757 (dehydrated at 600° C.) silica was thenadded to the activated metallocene mixture and reacted for 2 hrs. Thesupported catalysts were filtered onto a medium glass frit, washed withhexane and dried in vacuo.

Example 1

Ethylene-hexene copolymers were made by reacting ethylene with hexeneusing supported (n-PrCp)₂HfMe₂ catalyst and differentactivator/co-activator combinations. The data indicate that theactivator/co-activator combinations greatly affect the performance andcomposition of the copolymers as well as the polymerization dynamics.

Catalyst Preparation: Table 1 shows the materials used in preparing thecatalysts of this study. The amounts of materials were selected to givethe calculated metal loadings shown in Table 1. The level of TMA wasincreased by addition of neat TMA or decreased by reaction withtriphenylmethanol. This reaction preferentially removes the TMA overother Al-methyl species. In this reaction a highly pyrrophoric whitesolid was formed in addition to small amounts of triphenylethane. Thesolid was insoluble in toluene and was filtered from the MAO solutionbefore using in supportation. The supported catalysts were filtered ontoa medium glass frit, washed with hexane, dried in vacuo and analyzed asshown in Table 2. The supported catalyst systems (SCSs) were theninjected with nitrogen into the polymerization reactor as describedbelow.

TABLE 1 Calculated Values* (nPr-Cp)₂HfMe₂ MAO Added TMA Ph₃COH ES 757 AlHf Al/Hf Catalyst (g) (g) (g) (g) (g) Wt % Wt % mole ratio 36 0.62 39.70 0 62.5 7.3 0.35 135 37 0.62 45 0 3.85 62.5 7.7 0.34 146 39 0.67 39.70.35 0 74.3 6.4 0.32 129 41 0.79 39.7 1.3 0 82 6.2 0.35 115 44 0.83 45 04.35 86.4 5.8 0.35 107 42 0.62 39.7 0 0 62.5 7.3 0.35 135 43 0.79 39.71.3 0 80 6.3 0.36 113 46 1.08 63.4 0 0 42.5 14.0 0.73 124 *based uponsolution of MAO/TMA/Catalyst compound prior to contact with support.

TABLE 2 ICPES on polymer product Al/Hf Measured by Unknown Al Hf mole Si¹H NMR Integration Catalyst (ppm) (ppm) ratio (ppm) % TMA* Units* 3614.8 0.29 37 166 9.3 118 1131 8.2 0.63 39 211 9.9 141 1131 17.3 0.16 41241 14.2 112 1834 23 0.32 44 179 16 74 1941 9.2 0.37 42 167 8.2 135 94214.9 0.36 43 211 11.7 119 1480 21 0.20 46 94 5 124 257 14.9 0.36*measured on MAO solution prior to contact with catalyst compound orsupport.

Prior to being deposited on silica, the weight percent of TMA as totalAluminum-methyl species in MAO solutions was quantitatively determinedby ¹H NMR using the method disclosed in Donald W. Imhoff, Larry S.Simeral, Samuel A. Sangokoya, and James H. Peel, Organometallics, 1998,No. 17, pp. 1941-1945. MAO samples (30 wt % in toluene) were dissolvedin THF-d8 at least 5:1 by volume and ¹H NMR spectra taken on a Bruker250 MHz instrument (see FIGS. 1 and 2). Three Al-Me species weredistinguished: 1) a first broad signal due to oligomeric MAO from −0.2to −1.1 ppm (OAl-Me)_(x) which has the average formula(O_(0.8)AlMe_(1.3))_(x); 2) a second signal due to the THF-complexed TMAwas identified within the broad first signal at −0.9 ppm; and 3) a thirdsmaller up-field peak was identified within the broad first signal ataround −0.55 ppm of unknown formula. The wt % of TMA as total Al wasdetermined by integration after baseline correction (as calculated byBruker XWIN-NMR version 2.1 software using the polynomial function).Representative ¹H NMR spectra illustrating this method are shown inFIGS. 1 and 2. The proton shifts were assigned based on referencing theresidual downfield peak in deuterated THF as 3.58 ppm. The integrationunits were defined on the basis of the TMA peak are being normalized to3.0. In addition, the relative amount of the unknown species was alsodetermined and reported in Table 2. Surprisingly, the amount of unknownspecies was inversely proportional to the TMA level.

Polymerizations

The catalysts were screened in a laboratory gas phase reactor having afluidized bed reactor equipped with devices for temperature control,catalyst feeding or injection equipment, gas chromatograph analyzer formonitoring and controlling monomer and gas feeds, and equipment forpolymer sampling and collecting. The reactor consists of a 6″ (15.24 mm)diameter bed section increasing to 10″ (25.4 mm) at the reactor top. Gascomes in through a perforated distributor plate allowing fluidization ofthe bed contents and polymer sample is discharged at the reactor top.The reactor was operated as shown in Table 3. Catalysts 36 to 41 wererun with a low hydrogen concentrations. The other catalysts, 42 to 46,were run with a higher concentration of hydrogen. The temperature of thereactor was maintained at 165° F. (74° C.). An ethylene partial pressureof 105 psi (0.7 MPa) was used.

TABLE 3 Reactor Conditions Hydrogen Hexene/ Moles Ethylene HexeneEthylene Catalyst (ppm) Flow Ratio (Mole %) (Mole %) 36 130 0.04 0.2 3537 170 0.08 0.39 35 39 170 0.08 0.39 35 41 170 0.08 0.39 35 44 210 0.0780.37 35 42 210 0.078 0.37 35 43 210 0.078 0.37 35 46 210 0.078 0.37 35

Polymer Characterization

The polymers produced were characterized as shown in Tables 4 to 9.

TABLE 4 MI Density Tm Tc Hc Catalyst (dg/min) MIR (g/cc) (° C.) Hf (J/g)(° C.) (J/g) 36 1 26 0.929 37 0.25 0.916 118.6 141.5 103.9 −102.5 390.57 0.916 118.6 140.2 105.4 −102.9 41 0.68 23 0.917 118.9 141.7 106.1−100.8 44 0.7 0.916 118.4 116.9 102 −121.1 42 1.2 0.917 118.2 123.5 103−126.5 43 1.1 22 0.917 117.9 123.1 103 −123.8 46 1.1 0.917 117.2 121 102−124.1 X 1.0 34 0.921 122.42 106.6 109.4 −110.3 Y 0.95 20 0.918

Comparative polymer X is an LLDPE (ethylene hexene copolymer) producedin the gas phase (ethylene partial pressure greater than 220 psi, 75°C.) using bis(nPr-Cp)HfMe₂ and methylalumoxane (30 wt % MAO in toluenewith about 5% TMA). Comparative polymer Y is an LLDPE (ethylene hexenecopolymer) produced in the gas phase (ethylene partial pressure lessthan 190 psi, 85° C.) using bis(nPr-Cp)HfMe₂ and methylalumoxane (30 wt% MAO in toluene with about 5% TMA).

TABLE 5 Cat- Mw/ Mz/ alyst Mn{circumflex over ( )} Mw{circumflex over( )} Mz{circumflex over ( )} Mn Mw 68-70* 84* 90* 36 42572 106896 2050092.5 1.9 31 42 27 37 53817 137570 265314 2.6 1.9 73 19 8 39 43474 136138289182 3.1 2.1 68 24 8 41 48823 135601 287932 2.8 2.1 68 26 6 44 38940109245 235586 2.8 2.2 72 21 8 42 34270 105065 230067 3.1 2.2 68 26 5 4337632 104459 218357 2.8 2.1 70 24 6 46 41384 106698 226105 2.6 2.1 71 227 X 32600 129800 361700 4.0 2.8 44 37 19 Y 38695 125998 269429 3.3 2.168 24 8 {circumflex over ( )}measured by GPC, *Weight PercentComposition by TREF Peak Elution Temp (68° C. to 70° C., 84° C., 90° C.)Cross Fractionation Analysis performed by PolyChar, Valencia, Spain.

Analysis shows the polymers contain three fractions having differenthexene contents: lower density, medium density and higher densitymaterials. Specifically, the most soluble materials have a peak elutiontemperature between 68° C. and 70° C. This material contains most of theHexene in the resins. It contains the lowest density materials in theresins. These lower density materials composed between 31% and 73% ofthe resins’ total mass. Another fraction has a peak elution temperatureof about 84° C. This fraction contains medium density components of theresins. These medium density materials compose 19% to 42% of the resins.The final fraction contains higher density materials. This fraction hasa peak elution temperature of about 90° C. It contained 5% to 8% of theresins for all resins except for the resin made from catalyst 36. Twentyseven percent (27%) of the resin made from catalyst 36 is a higherdensity material.

The ethylene copolymers were analyzed using ¹³C NMR spectroscopy (seeTable 6).

TABLE 6 ¹³C NMR Analysis of Ethylene Hexene Copolymers Catalyst Mole % HMole % E HHH HHE EHE HEH HEE EEE 36 1.6 98.4 0.0001 0.0004 0.0156 0.00020.0311 0.9527 37 3.4 96.6 0.0006 0.0018 0.0323 0.0025 0.0615 0.9013 393.5 96.5 0.0003 0.0020 0.0331 0.0020 0.0636 0.8990 41 3.36 96.64 0.00020.0020 0.0318 0.0021 0.0612 0.9028 44 3.51 96.49 0.0003 0.0018 0.03350.0025 0.0635 0.8984 42 3.24 96.76 0.0003 0.0017 0.0309 0.0022 0.05850.9064 43 3.29 96.71 0.0000 0.0019 0.0313 0.0019 0.0601 0.9048 46 3.2196.79 0.0003 0.0014 0.0309 0.0021 0.0586 0.9068 46 3.35 96.65 0.00030.0017 0.0318 0.0019 0.0616 0.9027 Y 3.1 96.9 0.0000 0.0015 0.02890.0017 0.0574 0.9107 X 3.31 96.69 0.0004 0.0009 0.0254 0.0014 0.04880.9231

TABLE 7 ¹³C NMR Analysis of Ethylene Hexene Copolymers Average RunAverage Ethylene Butyls per Catalyst r1r2 Number Run Length 1000 Carbons36 1.16 1.6 0.62 7.8 37 1.27 3.3 0.29 16.2 39 1.04 3.4 0.29 16.5 41 1.043.3 0.30 15.9 44 0.94 3.4 0.28 16.6 42 1.07 3.1 0.31 15.4 43 0.85 3.20.30 15.6 46 0.94 3.1 0.31 15.3 46 1.01 3.3 0.30 15.8 X 1.21 2.6 0.3812.7

The polymers produced were processed through an Automated PolymerCompounder mini-extruder operated using counter rotating intermeshingtwin screws operated at 50 RPM and 190° C. The formulation was passedthrough the extruder three times. After a strand from any pass throughthe extruder was completed, it was cut into pellets and reintroducedinto the extruder. Compression-molded films were then made using aFontijne Press operated at a maximum temperature of 180° C. and pressureof 125 K Newtons (193 kPa). Copolymer samples were placed between thepress' platens heated at 180° C., and heated without being underpressure for 22 min. Then the platens were closed and the pressureincreased to 125 K Newtons (28 psi/193 kPa). The samples were heated at190° C. under a 125 K Newtons (193 kPa) of pressure for about 20 min.Then, the platens were opened and the sample cooled to room temperature.The bottom and top platens were cooled using tap water. The sampledcooled at about 18° C./min to about 75° C./min, and then the coolingrate decreases exponentially until the sample reaches 30° C. over about14 min

ISO 37:2005 Type 3 Test specimens were stamped out of the compressionmolded films using a commercial Clicker Press and die. The rectangularshaped test specimens were 8.5 mm wide by 50.8 mm long by the gauge ofthe film, which ranged from 0.07 mm to 0.15 mm (2.7-5.9 mils, 68.6-150.0microns). The film's gauge is provided below along with its Tensile testresult.

Tensile Testing of compression molded films (Tensile Strength, 1% SecantModulus, MD and TD) was performed according to ASTM D-882. TheIso37:2005 Type 3 test specimens were evaluated using a LaboratoryInstron Tensile tester Instron Model 5565. Three to six test specimensof each film were evaluated using the tester fitted with rubber facedgrips and a 1 Newton load cell. The Instron was operated using aninitial Grip-to-Grip width of 25.4 mm and a test speed of 200 mm/min.Jaws separation prior to testing was 35 mm, from which strains werecalculated assuming affine deformations. All strain values are in termsof the grips' separation distance. All stresses are reported as“engineering” values, i.e., stresses based on the originalcross-sectional area of the specimen, taking no account of reducedcross-section as a function of increased strain.

The primary and secondary Tensile at Yield points of each sample weredetermined as the maximum in the tensile curve between 7% and 40%elongation.

The data are reported in Tables 8A to 8D.

TABLE 8A Film Youngs Catalyst Thickness Modulus Secant Modulus (MPa) ID(mm) (MPa) 1% 2% Avg Avg Avg Avg 36 0.908 450.3 80.84 173.59 37 0.101265.0 46.85 101.66 39 0.104 268.4 45.82 105.72 41 0.997 259.5 41.22108.67 44 0.107 219.2 44.14 108.01 42 0.101 289.5 55.91 123.59 43 0.072271.7 44.39 114.65 46 0.095 235.5 51.50 114.16 X 0.088 283.9 — — Y 0.064319.3 — —

TABLE 8B Yield Point Yield Primary Secondary Stress Strain Stress StrainStress Strain Catalyst ID (MPa) (%) (MPa) (%) (MPa) (%) 36 18.3 14.418.1 18.3 — — 37 12.6 73.8 12.2 19.5 12.6 68.3 39 12.4 64.7 12.1 18.612.7 65.4 41 12.3 74.2 11.9 18.6 12.3 71.7 44 12.0 26.0 12.0 26.0 12.376.0 42 12.8 60.7 12.7 18.7 12.7 59.3 43 12.5 68.0 12.4 17.0 12.5 68.746 26.0 11.95 12.8 26.0 13.0 76.0 X 21.5 13.7 13.7 20.8 13.6 82.3 Y 16.414.7 14.7 18.5 14.1 40.0

TABLE 8C Tensile Stress @ indicated Elongation Catalyst Elongation ID100% 200% 300% 400% 500% 700% 36 16.22 16.0 16.7 19.0 20.8 28.4 37 12.3912.9 14.4 16.7 19.9 30.7 39 12.26 12.8 14.3 16.6 20.3 32.8 41 12.16 12.513.7 15.8 18.8 31.3 44 12.34 12.5 13.2 15.0 17.4 32.8 42 12.54 12.9 14.216.7 20.2 33.6 43 12.22 12.8 13.8 16.3 20.0 34.9 46 12.85 13.1 13.8 15.017.3 24.0 X 14.18 14.6 15.2 17.95 21.2 23.6 Y 13.9 14.9 15.2 17.7 20.4

TABLE 8D Ultimate Strain Hardening Catalyst Stress Strain Strain/StressModulus ID (MPa) (%) Ratio (MPA/%) 36 40.08 912.01 22.8 0.059 37 35.88768.32 21.4 0.075 39 38.36 765.11 19.9 0.087 41 39.67 793.51 20.0 0.09144 35.41 942.56 26.6 0.053 42 45.81 834.32 18.2 0.102 43 45.32 790.5417.4 0.116 46 32.74 891.67 27.2 0.046 X 43.7 749 17.1 0.105 Y 41.0 887.221.6 0.072

Compression-molded circular disks were made from the polymer processedthrough the extruder using a Fontijne Press as described above for theCompression-molded films. The disks were evaluated according to ASTMD-1922 for Elmendorf Tear performance. Specimens used in this testinghad normally distributed gauges and tear values that were understatistical process control: with Coefficients of Variance (Cv*) lessthan 10%. The results of the analysis are shown in the following Table8E.

TABLE 8E Elmendorf Tear Gauge (mils) Tear (grams) Tear Standard Standard(grams/mil) Catalyst ID Average Deviation Cv* Average Deviation Cv*Average 37 3.0 0.2 6 967.1 64 7 325 39 2.8 0.2 6 901.9 83 9 310

The poor performance of the copolymer made from catalyst 44 is possiblydue to its exceptionally low Aluminum/Hafnium ratio of 74:1.

For reference purposes the following data is included.

TABLE 9A Selected Physical and Mechanical Properties of ZN-LLDPE^(#) andm-LLDPE films.* Comonomer MD 1% Secant MD Yield MD Ultimate Type/LoadingMI Density Modulus Stress Properties Resin (mole %) (g/10 min) (g/cc)(MPa) (MPa) (%) (MPa) LL 1001^(#) C4/3.6 1.0 0.918 220 9.4 590 57.0 LL3001^(#) C6/3.6 1.0 0.917 200 9.0 500 58.0 Exact 4056* C6/>3.5 2.2 0.83330 3.5 390 64.3 Exact 4151* C6 >3.5 2.2 0.889 56 5.4 400 84.8 ExceedC6/3.5 1.0 0.912 131 7.4 500 72.6 1012* Exceed C6/1.5 1.0 0.918 183 9.2540 74.5 1018* Exceed C6/<1.5 1.0 0.923 240 11.0 542.0 65.0 1023* *Datain Tables 9A and 9B are taken from ExxonMobil's technical data sheets.

TABLE 9B Selected Physical and Mechanical Properties of ZN-LLDPE^(#) andm-LLDPE films.* MD Elmendorf Tear Ultimate TD/ Dart Strain/Stress MD (g/TD (g/ MD Drop (g/ Resin Ratio micron) micron) Ratio micron)* LL1001^(#) 10.4 4.0 16.0 — 4.0 LL 3001^(#) 8.6 17.3 17.3 — 5.5 Exact 4056*6.1 2.2 5.3 — 32.4 Exact 4151* 4.7 3.5 11.0 — 37.0 Exceed 1012* 6.9 8.313.0 1.6 32.2 Exceed 1018* 7.2 11.0 18.1 1.6 22.4 Exceed 1023* 8.3 7.021.1 3.0 7.4 *Data in Tables 9A and 9B are taken from ExxonMobil'stechnical data sheets.

Table 10 shows selected tensile properties of thin compression moldedplaques (at about 16% elongation) of the polymers in Tables 9A and 9Band prepared as described above.

TABLE 10 Selected Physical and Mechanical Properties of ZN-LLDPE^(#) andm-LLDPE resins.* Catalyst/ Youngs MD Yield MD Ultimate Properties ResinModulus Stress Strain Stress Strain/ Type (MPa) (MPa) (%) (MPa) StressRatio LL 1001 308 14.5  1194 36.1 33 LL 3001 303 14.0  1050 33.2 32Exact 4056 12  3.6* 592 31.6 19 Exact 4151 16  5.7* 698 51.8 13 Exceed1012 251 12.7  978 46.6 21 Exceed 1018 304 14.56 997 46.5 21 Exceed 1023342 15.8  900 35.8 25

Several comparative blown films of ethylene-hexene copolymers (3 mole %hexene, melt index ratio 31.4 (ASTM D-1238), density 0.921 g/cc) wereprepared according to the general procedure in Example 1 of US2009/0297810 (U.S. Ser. No. 12/130,135, filed May 30, 2008) and anyreferences referred to therein. The specific conversion conditions aredescribed in Table 11 Å and the mechanical properties are described inTable 11B.

TABLE 11A Selected Processing Conditions Die Diameter Die Gap OutputFilm gauge FLH Trail (mm) (mm) (kg/h) BUR (μm) (mm) DDR STR PRT 55 2002.5 130.0 1.25 50 600 33.48 1.62 2.17 75 200 2.5 78.0 1.50 50 300 27.901.61 2.07 24 160 1.4 200 2.5 20 810 7.81 3.18 0.65 16 160 1.4 160 3 20730 19.53 1.27 2.34 13 160 1.4 110 3.00 20 540 19.53 1.93 1.54 14 1601.4 130 2.00 20 630 29.29 2.99 1.13 BUR = blow up ratio, FLH is frostline height, DDR is draw down ratio, STR is stretch rate, PRT is processtime.

TABLE 11B Selected Properties of Films 1% Secant MD Stress ElmendorfTensile at Modulus at 100% Tear Dart Break Elongation at (MPa)Elongation (g/micron) Drop (MPa) Break (%) Trail MD TD (MPa) MD TD(g/micron) MD TD MD TD 55 237 268 15 15.32 20.99 12.21 75.4 52.6 369 60175 — — 14.34 13.65 17.77 15.81 46.2 42.1 481 1016 24 250 298 16.17 24.9220.59 29.20 75.6 41.6 282 621 16 243 297 15.1 18.11 18.43 51.53 67.250.6 314 631 13 265 356 15.28 21.29 20.97 54.03 55.8 48.7 573 656 14 253322 19.57 51.15 32.20 8.50 61.4 46.1 522 601

All documents described herein are incorporated by reference herein,including any priority documents and/or testing procedures to the extentthey are not inconsistent with this text. As is apparent from theforegoing general description and the specific embodiments, while formsof the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited thereby. Likewise, the term “comprising” is consideredsynonymous with the term “including” for purposes of Australian law.Likewise the term “comprising” encompasses the terms “consistingessentially of,” “is,” and consisting of and anyplace “comprising” isused “consisting essentially of,” “is,” or “consisting of” may besubstituted therefor.

1. A process for polymerizing olefins in which the amount oftrimethylaluminum in a methylalumoxane solution is adjusted to be from 1to 25 mole %, prior to use as an activator, where the mole %trimethylaluminum is determined by ¹H NMR of the solution prior tocombination with any support.
 2. The process of claim 1, wherein themethylalumoxane solution is present in a catalyst system also comprisinga metallocene transition metal compound.
 3. The process of claim 1,wherein the amount of trimethylaluminum is adjusted by removingtrimethylaluminum.
 4. The process of claim 2, wherein the catalystsystem in methylalumoxane solution prior to combination with any supporthas an aluminum to transition metal molar ratio of 175:1 to 50:1.
 5. Theprocess of claim 2, wherein the metallocene transition metal compound isrepresented by the formula:Cp ^(A) Cp ^(B)HfX*_(n) wherein each X* and each Cp group is chemicallybonded to Hf, n is 1 or 2, Cp^(A) and Cp^(B) may be the same ordifferent cyclopentadienyl ligands or ligands isolobal tocyclopentadienyl, either or both of which may contain heteroatoms andeither or both of which may be substituted.
 6. The process of claim 5,wherein Cp^(A) and Cp^(B) are independently selected from the groupconsisting of cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl,and substituted derivatives of each.
 7. The process of claim 2, whereinthe metallocene transition metal compound comprises a bis(n-C₃₋₄ alkylcyclopentadienyl) hafnium dialkyl or dihalide.
 8. The process of claim2, wherein the metallocene transition metal compound comprisesbis(n-propyl cyclopentadienyl) hafnium dichloride and/or bis(n-propylcyclopentadienyl) hafnium dimethyl.
 9. The process of claim 2, whereinthe catalyst system is contacted with one or more olefins.
 10. Theprocess of claim 9, wherein the polymerization process is a gas phaseprocess.
 11. The process of claim 10, wherein the olefins compriseethylene and the ethylene partial pressure in the gas phasepolymerization is from 50 to 250 psi (345 to 1724 kPa).
 12. The processof claim 9, wherein the polymerization process is a slurry phaseprocess.
 13. The process of claim 9, wherein the olefins compriseethylene and at least one C₃ to C₂₀ olefin.
 14. The process of claim 13,wherein the C₃ to C₂₀ olefin is one or more of propylene, butene,hexene, and octene.
 15. The process of claim 13, wherein the C₃ to C₂₀olefin is hexene.
 16. The process of claim 1, wherein the amount oftrimethylaluminum is adjusted by adding trimethylaluminum to themethylalumoxane solution.
 17. A process for polymerizing olefins inwhich the amount of an unknown species present in a methylalumoxanesolution is adjusted to be from 0.10 to 0.65 integration units, prior touse as an activator, where the unknown species is identified in the ¹HNMR spectra of the solution prior to combination with any support. 18.The process of claim 17, wherein the methylalumoxane solution is presentin a catalyst system also comprising a metallocene transition metalcompound.
 19. The process of claim 17, wherein trimethylaluminum addedto or removed from the methylalumoxane solution.
 20. The process ofclaim 17, wherein the amount of the unknown species is adjusted byadding or removing trimethylaluminum to or from the methylalumoxanesolution.
 21. The process claim 18, wherein the catalyst system has analuminum to transition metal molar ratio of 175:1 to 50:1.
 22. Theprocess claim 18, wherein the metallocene transition metal compound isrepresented by the formula:Cp ^(A) Cp ^(B)HfX*_(n) wherein each X* and each Cp group is chemicallybonded to Hf, n is 1 or 2, Cp^(A) and Cp^(B) may be the same ordifferent cyclopentadienyl ligands or ligands isolobal tocyclopentadienyl, either or both of which may contain heteroatoms andeither or both of which may be substituted.
 23. The process of claim 18,wherein Cp^(A) and Cp^(B) are independently selected from the groupconsisting of cyclopentadienyl, indenyl, tetrahydroindenyl, fluorenyl,and substituted derivatives of each.
 24. The process of claim 18,wherein the metallocene transition metal compound comprises a bis(n-C₃₋₄alkyl cyclopentadienyl) hafnium dialkyl or dihalide.
 25. The processclaim 18, wherein the metallocene transition metal compound comprisesbis(n-propyl cyclopentadienyl) hafnium dichloride and/or bis(n-propylcyclopentadienyl) hafnium dimethyl.
 26. The process of claim 18, whereinthe catalyst system is combined with one or more olefins.
 27. Theprocess claim 26, wherein the polymerization process is a gas phaseprocess.
 28. The process of claim 27, wherein the olefins compriseethylene and the ethylene partial pressure in the gas phasepolymerization is from 50 to 250 psi (345 to 1724 kPa).
 29. The processof claim 26, wherein the polymerization process is a slurry phaseprocess.
 30. The process of claim 26, wherein the olefins compriseethylene and at least one C₃ to C₂₀ olefin.
 31. The process of claim 30,wherein the C₃ to C₂₀ olefin is one or more of propylene, butene, hexeneand octene.
 32. The process of claim 30, wherein the C₃ to C₂₀ olefin ishexene.
 33. A copolymer comprising ethylene and from 0.5 to 25 mole % ofC₃ to C₂₀ olefin comonomer, said copolymer having: 1) a ratio ofUltimate Tensile Stress to Tensile Stress at 100% elongation of 2.5 ormore; 2) a ratio of Ultimate Tensile Stress to Tensile Stress at 300%elongation of 2.4 or more; 3) a ratio of Ultimate Tensile Stress toTensile Stress at the primary yield point of 2.9 or more; 4) a densityof 0.910 g/cm³ or more; 5) a 1% secant modulus of 30 to 100 MPa; 6) aTensile Stress of Y MPa or more, where Y=(0.0532)*Z−8.6733 and Z is thepercent strain and is a number from 500 to 2000; and 7) a 1% secantmodulus of 40 to 100 MPa.
 34. The copolymer of claim 33, wherein thecopolymer comprises ethylene and from 0.5 to 25 mole % of hexene. 35.The copolymer of claim 33, wherein the copolymer has an Mw of from 5000to 1,000,000 g/mol.
 36. A film comprising the copolymer of claim
 33. 37.A copolymer comprising ethylene and from 0.5 to 25 mole % of C₃ to C₂₀olefin comonomer, said copolymer having: a tensile stress at thesecondary yield point of 15 MPa or more; a ratio of ultimate tensilestrain to ultimate tensile stress of 19.9 or more; a tensile stress at200% (MPa) that is greater than the tensile stress at the at thesecondary yield point (MPa); a comonomer triad ([HHH] triad) of 0.0005mole % or more, preferably 0.0006 mole % or more; a density of 0.910g/cm³ or more; and a 1% secant modulus of 30 to 100 MPa.
 38. Thecopolymer of claim 37, wherein the copolymer comprises ethylene and from0.5 to 25 mole % of hexene.
 39. The copolymer of claim 37, wherein thecopolymer has an Mw of from 5000 to 1,000,000 g/mol.
 40. A filmcomprising the copolymer of claim
 37. 41. A process to produce blockcopolymers comprising adjusting the amount of trimethyl aluminum in amethylalumoxane solution prior to use as an activator to obtain [HHH]triad fractions that differ by at least 5% relative to each other. 42.The process of claim 41, wherein the process is a continuous process andthe trimethylaluminum is adjusted on-line prior to entry into apolymerization reactor.
 43. The process of claim 42, wherein thetrimethylaluminum is added intermittently to the methylalumoxanesolution before or after combination with a catalyst compound.
 44. Theprocess of claim 1, wherein the trimethylaluminum is adjusted by addinga Bronsted Acid to the methylalumoxane solution before or aftercombination with a catalyst compound.
 45. The process of claim 19,wherein the trimethylaluminum is adjusted by adding a Bronsted Acid tothe methylalumoxane solution before or after combination with a catalystcompound.
 46. The process of claim 41, wherein the trimethylaluminum isadjusted by adding a Bronsted Acid to the methylalumoxane solutionbefore or after combination with a catalyst compound.